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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Diseases of the colon & rectum 41 (1998), S. 1523-1528 
    ISSN: 1530-0358
    Schlagwort(e): Diverticular disease ; Complications ; Surgery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract PURPOSE: The natural history of patients admitted because of acute diverticulitis is largely unknown, and the selection of patients for surgical treatment varies notably. This study presents our experience concerning the outcome for 366 patients admitted during a 10-year period. METHODS: Three hundred sixty-six patients admitted to our hospital with acute diverticulitis from 1981 to 1990 were identified from a computer database, and their clinical data up to the end of 1996 were reviewed from the database and patient records. RESULTS: There were significantly more males than females in the age group less than 50 years old, and young males underwent surgical treatment during the first treatment period more frequently than the others. Young patients were operated on without mortality, and all their temporary colostomies were closed. Older patients died more often of diseases unrelated to the diverticular disease during the years after the first episode of acute diverticulitis. Recurrences of diverticular disease developed in 22 percent of patients, and they were significantly more common in patients less than 50 years old than in the older age groups. Males less than 50 years old more often developed complications of diverticular disease after two hospital admissions. CONCLUSIONS: Males first admitted when less than 50 years of age undergo more primary operations and develop more recurrences of diverticular disease than do older people. Based on our data, however, we recommend surgery for all patients after two episodes of acute diverticulitis that resolves after conservative treatment with antibiotics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Diseases of the colon & rectum 41 (1998), S. 654-657 
    ISSN: 1530-0358
    Schlagwort(e): Ileoanal reconstruction ; Complications ; Blind loop ; Surgical management ; Surgical technique
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract PURPOSE: To demonstrate a simple and effective repair of a poorly constructed ileal J-pouch with an extensive long efferent limb. METHOD: A retrospective case review was performed. RESULTS: The surgical procedure described preserves additional ileum and enlarges the ileal reservoir. The procedure succeeded in resolving the patient's complaints of partial obstruction, weight loss, and increased stool frequency. At five-month follow-up, the patient was doing well with three to six stools daily. Evaluation of the new ileal J-pouch showed no signs of inflammation, and the pouch size measured more than 20 cm compared with 12 cm preoperatively. CONCLUSIONS: Repair of a long efferent limb by this simple stapling technique is feasible, simple, and effective, with an excellent clinical result. It preserves valuable small intestine and enlarges the capacity of the reservoir, leading to better functional outcome.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Diseases of the colon & rectum 41 (1998), S. 1023-1028 
    ISSN: 1530-0358
    Schlagwort(e): Diverticulitis ; Computed tomography ; Hospital costs ; Complications ; Surgery ; Accuracy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract PURPOSE: The purpose of this study was to evaluate the use and timing of computed tomography in the treatment of patients with acute left-sided diverticulitis. METHODS: We reviewed our four-year experience of 47 patients with the diagnosis of acute diverticulitis. We have evaluated the benefits of admissionvs. delayed computed tomography in patients with this diagnosis. RESULTS: Of the 47 patients, 17 were diagnosed on clinical grounds alone, treated, and released. Thirty patients had their clinical diagnoses of diverticulitis evaluated with either computed tomographic scan (26) or laparotomy (4). Eleven of those 30 (36 percent) patients were found to have normal computed tomographic scans, indicating inaccurate clinical diagnosis, and all patients who underwent laparotomy had the pathologic diagnosis of diverticulitis. Six of the 47 patients had abscesses, but only 2 were identified at the time of admission. The remaining four abscesses were identified on delayed computed tomographic scans after failure of medical therapy. Thirty-seven hospital days were used by patients with inaccurate diagnoses before their computed tomographic scans. Analysis of cost revealed that a computed tomographic scan for all 47 patients would have cost less than the expense of admission for just the 11 patients who had normal computed tomographic scans. CONCLUSION: Routine admission computed tomographic scan for patients with acute diverticulitis leads to more accurate diagnosis, earlier identification of complications, and possible decreased hospital costs.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Diseases of the colon & rectum 41 (1998), S. 1587-1589 
    ISSN: 1530-0358
    Schlagwort(e): Ileal-pouch-anal-anal anastomosis ; Complications ; Surgical technique
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract PURPOSE: A novel technique is described for pouch reconstruction after failed restorative proctocolectomy and pouch excision. METHODS: Surgery was undertaken in two patients who had undergone restorative proctocolectomy with subsequent excision of the ileal J-pouch after necrosis. At revisional surgery it was technically impossible to form a pouch using the terminal ileum because of mesenteric shortening. A new 18-cm J-pouch was formed with a jejunal segment. After selective division of axial vessels, adequate length was obtained to allow formation of a jejunal-pouchanal anastomosis. The small bowel distal to the pouch was interposed between the proximal jejunum and J-pouch and a defunctioning stoma was made. RESULTS: The postoperative course was uneventful in both cases. The functional results at 3 and 12 months after stoma closure were good, with five to seven bowel movements per day and complete continence. CONCLUSION: Shortening of the terminal ileal mesentery may preclude the formation of an ileal pouch in patients undergoing salvage surgery after failed restorative proctocolectomy. This novel technique of jejunal J-pouch formation and small-bowel interposition has value as an alternative to definitive ileostomy or Kock's pouch in such patients.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Diseases of the colon & rectum 41 (1998), S. 254-257 
    ISSN: 1530-0358
    Schlagwort(e): Insufficiency fractures ; Radiation injury effects ; Radiotherapy ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract PURPOSE: The report contained herein presents a patient who developed severe back pain because of bilateral sacral insufficiency fractures after pelvic radiation for rectal carcinoma. METHODS: This is a case report and review of the literature for a rare complication of pelvic radiation. RESULT: The patient was diagnosed by computerized tomography and radionuclide bone scans. Bed rest and analgesia followed by rehabilitation provided good relief of the symptoms. CONCLUSION: A rare complication of pelvic radiation is insufficiency fractures of the pelvis. Early detection is important, because significant morbidity may result from delaying treatment. Unawareness of this complication may lead to diagnostic difficulties and unnecessary work-up.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1534-4681
    Schlagwort(e): Pelvic exenteration ; Gynecologic malignancy ; Complications ; Antibiotics ; Heparin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background: Since pelvic exenteration for the treatment of recurrent gynecologic malignancy first was described, reported rates of morbidity and mortality have declined steadily. However, the factors responsible for this decline have never been clearly delineated. Methods: We reviewed the charts of 154 patients who underwent pelvic exenteration for gynecologic malignancy between 1954 and 1994. Charts were abstracted for details of the surgical procedure, pathologic findings, postoperative management, short- and long-term complications, time to recurrence, and overall survival. Results: Seventy-two patients (47%) experienced 95 identifiable postoperative complications, resulting in death in 22 patients (14%). The rate of infectious complications declined to a statistically significant degree between the first two decades and latter two decades of the study (odds ratio [OR] 0.28, 95% CI 0.11–0.69). The use of routine prophylactic antibiotics was associated with this decline in infectious complications (OR 0.25, 95% CI 0.07–0.83). The use of preoperative subcutaneous heparin was associated with a reduction in thrombotic complications from 5 of 100 patients to 0 of 54 patients (P=.11), as well as a significant reduction in overall risk of complications (OR 0.53, 95% CI 0.33–0.85) and risk of postoperative mortality (OR 0.19, 95% CI 0.05–0.80). There was a significant reduction in overall risk of postoperative complications with both intensive care unit monitoring postoperatively (OR 0.65, 95% CI 0.43–0.99) and routine postoperative monitoring with a pulmonary artery catheter (OR 0.61, 95% CI 0.38–0.98). Conclusions: Routine use of prophylactic antibiotics, prophylactic subcutaneous heparin, and intensive postoperative monitoring appear to have reduced morbidity from pelvic exenteration.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Clinical oral investigations 2 (1998), S. 73-76 
    ISSN: 1436-3771
    Schlagwort(e): Key words Inferior alveolar nerve ; Complications ; Endodontic treatment ; Surgical therapy ; Apicectomia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Overextension of filling material into the mandibular canal after root treatment in the lower jaw is a rare but serious complication. Mechanical compression, chemical neurotoxicity and local infection may cause irreversible nerve damage. A report on 11 patients with neurological complaints of the inferior alveolar nerve after endodontic treatment is summarised. The neurological findings are dominated by hypaesthesia and dysaesthesia. Half of the patients reported pain. Hyperaesthesia is found much more rarely. Nearly all the patients had a combination of one or more symptoms. Initial X-rays showed root filling material in the area of the mandibular canal. Nine cases were treated with apicectomy and decompression of the nerve; in two cases, extraction of the tooth was necessary. Only one patient reported persistent pain after surgery. If neurological complaints appear after root filling in the lower jaw, a nerve injury due to root filling material should be ruled out. In cases of overfilling, immediate apicectomy and decompression of the nerve with conservation of the tooth is often the treatment of choice; the tooth may be preserved and the best chance of avoiding permanent nerve damage is provided.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Neurosurgical review 21 (1998), S. 254-259 
    ISSN: 1437-2320
    Schlagwort(e): Complications ; fiberoptic device ; intracranial pressure monitoring
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Seventy-five patients with intracranial hypertension whose Glasgow Coma Score (GCS) was 8 or below and in whom intracranial pressure (ICP) was monitored were examined for complications of this procedure. In 20 of the 75 patients we used only an intraparenchymal fiberoptic ICP monitoring transducer, while, in the remaining 55 patients, who required CSF drainage, a ventricular drainage set (VDS) was used in addition to ICP monitoring. The duration of monitoring with the ICP transducer alone was approximately 5.1 ± 2.6 das (min. 1, max. 13) and that of ICP monitoring with VDS was 6.2 ± 3.1 days (min. 1, max. 13). In 8 cases a total of 9 complications were experienced (12 %). These complications were infection in 3 cases (4 %), epidural hematoma in 2 cases (2.7 %), disconnection in 2 cases (2.7 %) and contusion in 2 cases (2.7 %). Although none of the 44 patients who were monitored for less than 5 days experienced infection, 3 of the 31 patients monitored for longer than 5 days did experience infection (9.7 %) (p 〈 0.05). None of the 20 patients who underwent ICP monitoring only experienced infection. However, 3 of the 55 patients in whom the ventricular drainage set was implanted in addition to the transducer for ICP monitoring experienced infection (p 〈 0.05). Owing to its minimally invasive nature, low complication rate, and accuracy in monitoring the parenchyma pressure, the Camino fiberoptic intraparenchymal monitor has become the system of choice in our clinic.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Rechtsmedizin 8 (1998), S. 73-76 
    ISSN: 1434-5196
    Schlagwort(e): Key words Laparoscopy ; Complications ; Carbon ; dioxide embolism ; Confirmation ; Schlüsselwörter Laparoskopie ; Komplikationen ; Kohlendioxid-Embolie ; Nachweis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Rechtswissenschaft
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wird der Fall einer 30 Jahre alt gewordenen Patientin vorgestellt, welche während einer beabsichtigten gynäkologischen laparoskopischen Operation trotz sofortiger Reanimationsmaßnahmen akut starb. Die klinische Symptomatik entsprach einer akuten Gasembolie, insbesondere wegen einer sonographisch verifizierten intravasalen Gaspulsation. Bei der Obduktion 2 Tage postmortem wurde eine frische Perforation der linken Vena iliaca communis festgestellt. Eine Gasembolie des Herzens konnte nicht nachgewiesen werden. Es wird auf besondere physiko-chemische Bedingungen einer tödlichen CO2-Gasembolie hingewiesen. Voraussetzungen für den postmortalen Gasnachweis sind: umgehende Obduktion und Verzicht auf Kühlung der Leiche.
    Notizen: Abstract We report a case of a 30-year-old patient who – after unsuccessfull resuscitation – died during gynecological laparoscopy. Prefinal symptoms corresponded to acute gas embolism, particularly as ultrasonic examination revealed an intravascular gas pulsation. At autopsy, 2 days postmortem, a punction of the left common iliac vein was discovered but gas bubbles in the right heart could not be confirmed. Preconditions for fatal carbon dioxide embolism are stressed. To prove the presence of carbon dioxide gas postmortem, autopsy has to be performed as soon as possible and the corpse has to be stored without cooling.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Der Chirurg 69 (1998), S. 773-776 
    ISSN: 1433-0385
    Schlagwort(e): Key words: Laparoscopy ; Complications ; Carbon dioxide embolism ; Confirmation. ; Schlüsselwörter: Laparoskopie ; Komplikationen ; Kohlendioxid-Embolie ; Nachweis.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Tödliche Komplikationen bei endoskopischen Eingriffen sind insgesamt selten. Als häufigste Ursache wurden Verletzungen großer intraabdominaler Gefäße mit nachfolgender Blutung, aber auch mit Kohlendioxid (CO2)-Embolie beobachtet. Es wird der Fall einer 30 Jahre alt gewordenen Patientin vorgestellt, welche zu Beginn einer gynäkologisch-laparoskopischen Operation trotz sofortiger Reanimationsmaßnahmen akut starb. Die klinische Symptomatik entsprach einer akuten Gasembolie, insbesondere wegen einer sonographisch verifizierten Gaspulsation. Bei der Obduktion 2 Tage post mortem wurde eine frische Perforation der linken V. iliaca communis festgestellt. Eine Gasembolie des Herzens konnte nicht nachgewiesen werden. Dafür können die physikochemischen Eigenschaften des CO2 maßgeblich sein. Voraussetzungen für den postmortalen Gasnachweis sind: umgehende Obduktion und Verzicht auf Kühlung der Leiche.
    Notizen: Summary. Fatal complications during laparoscopy mostly originate from injury to major pelvic vessels, causing severe hemorrhage or carbon dioxide embolism. We report a case of a 30-year-old patient who – after unsuccessful resuscitation – died during gynecologic laparoscopy. The noted signs corresponded to acute gas embolism, particularly as ultrasound revealed intravascular gas pulsation. At autopsy, 2 days post mortem, a puncture of the left common iliac vein was discovered. Despite this, gas bubbles in the right heart could not be confirmed. Preconditions for fatal carbon dioxide embolism are stressed. To prove the presence of carbon dioxide gas post mortem, autopsy has to be performed as soon as possible and the corpse has to be stored without cooling.
    Materialart: Digitale Medien
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  • 11
    ISSN: 1279-8517
    Schlagwort(e): Ureter ; Abnormalities ; Embryology ; Calculi ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Partial ureteral duplication in an inverted Y is evidenced by the presence of a ureter duplicated at a variable level before reaching the bladder, in either an orthotopic or an ectopic position. A case of ureteral duplication at the level of the renal hilum with opening of a ureter at the level of the epididymis is reported. The description of this original case is compared with the data in the literature. The stages of organogenesis of the superior excretory pathway leading to ureteral ectopia and ureteral anomalies of number are reviewed.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1279-8517
    Schlagwort(e): Ureter ; Abnormalities ; Embryology ; Calculi ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé La duplication urétérale partielle en Y inversé se traduit par la présence d'un uretère se dédoublant à une hauteur variable avant d'atteindre la vessie, de façon orthotopique ou ectopique. Un cas de dédoublement urétéral au niveau du hile du rein avec abouchement d'un uretère ectopique au niveau de l'épididyme est rapporté. La description de ce cas original permet sa confrontation aux données de la littérature. Les étapes de l'organogenèse de la voie excrétrice supérieure aboutissant aux ectopies urétérales et aux anomalies urétérales de nombre sont rappelées.
    Notizen: Summary Partial ureteral duplication in an inverted Y is evidenced by the presence of a ureter duplicated at a variable level before reaching the bladder, in either an orthotopic or an ectopic position. A case of ureteral duplication at the level of the renal hilum with opening of a ureter at the level of the epididymis is reported. The description of this original case is compared with the data in the literature. The stages of organogenesis of the superior excretory pathway leading to ureteral ectopia and ureteral anomalies of number are reviewed.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    International journal of legal medicine 111 (1998), S. 93-96 
    ISSN: 1437-1596
    Schlagwort(e): Key words Cardiopulmonary resuscitation ; Active compression-decompression ; Complications ; Iatrogenic injury ; Myocardial rupture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Rechtswissenschaft
    Notizen: Abstract An 84-year-old woman was unsuccessfully resuscitated for 3 min using standard cardiopulmonary resuscitation (CPR), followed by 15 min of active compression-decompression (ACD). The autopsy revealed that death was due to myocardial infarction complicated by rupture of the infarcted area and pericardial tamponade was diagnosed. Furthermore, a series of rib fractures, a transverse fracture of the sternum, rupture of the pericardial sac, the right ventricle, both atria and lacerations of the ascending aorta, were found with no signs of a vital reaction. To our knowledge, such extensive cardiac injury after CPR has not been previously reported. It is suggested that the pre-existing pericardial tamponade, the age of the patient and the application of the ACD-device to incorrect areas of the chest contributed to the extent of the cardiac injury. This case further adds to the suspicion of an increased risk of cardiac injuries when using an ACD device for cardiac massage.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1433-0458
    Schlagwort(e): Schlüsselwörter Intubation ; tracheal: retrograd-geführt ; fiberoptisch ; Technik ; Komplikationen ; Training ; Key words Tracheal intubation ; Retrograde-guided fiberoptic technique ; Complications ; Training
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Retrograde or fiberoptic intubation techniques are recommended for patients in whom intubation is difficult; however, each method has its own limitations. Good results have been reported with a combination of both techniques, i.e. retrograde passage of a guidewire through the cricothyroid membrane to guide a fiberoptic bronchoscope. The practicality, success and complication rates of our retrograde-guided fiberoptic bronchoscopic technique (RGFT) were studied prospectively in 93 patients with obstructing tumors scheduled for laryngectomy. The technique showed itself to be successful, practical and safe, with negligible complications in 89/93 patients (96%). The ability to insert the bronchoscope by means of a guidewire and to direct the intubation procedure optically was found to be advantageous. Limitations were found in two patients with extreme obesity and in two other patients with advanced obstructive carcinomas of the larynx. Additionally, use of the tracheal puncture allows the RGFT to be integrated into clinical medical education as a preparatory exercise for emergency coniotomy.
    Notizen: Zusammenfassung Retrograde und fiberoptische Intubationstechniken werden für schwierig zu intubierende Patienten empfohlen, weisen aber jeweils methodenspezifische Limitationen auf. Gute Erfolge wurden mit einer Kombination beider Techniken, d.h. der retrograden Passage eines Führungsdrahts durch die Membrana cricothyreoidea und nachfolgenden Führung des Fiberbronchoskops beschrieben. In einer prospektiven Studie an 93 Patienten mit Hyopharynx-Larynx-Karzinom, die für eine Laryngektomie vorgesehen waren, wurden Durchführbarkeit, Erfolgsrate und Komplikationsrate der „retrograd-geführten fiberbronchoskopischen Technik” (RGFT) untersucht. Die Technik erwies sich bei 89/93 Patienten (96%) als relativ einfaches, praktikables und sicheres Verfahren mit vernachlässigbaren Komplikationen, das aufgrund der Führung des Bronchoskops durch den Führungsdraht sowie die optische Kontrolle des Intubationsvorgangs vorteilhaft war. Limitationen fanden sich bei 2 Patienten mit Adipositas permagna sowie bei 2 weiteren Patienten mit obstruierendem Larynxkarzinom. Aufgrund der erforderlichen Trachealpunktion ist die RGFT darüber hinaus als Vorübung zur Notfallkoniotomie unter optimalen Bedingungen in die klinische Routine integrierbar.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1433-0385
    Schlagwort(e): Key words: ASA score ; Risk evaluation ; Complications ; Laparoscopic cholecystectomy ; Contraindications. ; Schlüsselwörter: ASA-Klassifikation ; Risikoeinschätzung ; Komplikationen ; laparoskopische Cholecystektomie ; Kontraindikation.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Die laparoskopischen Cholecystektomie bietet eine Reihe von Vorteilen, denen eine erhöhte Gefährdung kardiopulmonal vorgeschädigter Patienten durch die hämodynamischen und respiratorischen Auswirkungen des Pneumoperitoneums gegenübersteht. In der Zeit von Juni 1990 bis Dezember 1995 wurden 19 Hochrisikopatienten (ASA IV) laparoskopisch und 26 Patienten mit gleichem operativem Risiko (ASA IV) konventionell cholecystektomiert. Bei insgesamt 11,1 % (n = 5) an intraoperativen, kardiopulmonalen Komplikationen traten diese in beiden Gruppen annähernd gleichhäufig auf. Allgemeine, postoperative Komplikationen sahen wir in 33,3 % (n = 15) aller Fälle, wobei die konventionell operierten Patienten vermehrt betroffen waren [46,2 % (n = 12) vs. 15,8 % (n = 3), p = 0,03]. Die Liegedauer war in der Gruppe der offen operierten Patienten mit 11,6 ± 5,6 Tagen im Vergleich zu 7,6 ± 5 (Gruppe der laparoskopisch operierten Patienten) verlängert (p = 0,01). Die Einstufung als Hochrisikopatient bedeutet insgesamt eine Erhöhung der perioperativen Komplikationsrate, wobei bei gleichem intraoperativen Risiko die postoperative Komplikationsrate bei laparoskopischer Cholecystektomie niedriger ist.
    Notizen: Summary. Laparoscopic cholecystectomy offers many advantages, but cardiopulmonary impaired patients may be endangered by the haemodynamic and respiratory effects of the pneumoperitoneum. Between June 1990 and December 1995, laparoscopic cholecystectomies were performed on 19 high-risk patients (ASA IV) and conventional cholecystectomies on 26 patients with the same operative risk (ASA IV). Out of 45 patients, 5 (11.1 %) suffered intraoperative cardiopulmonal complications. Three belonged to the group with laparoscopic cholecystectomy (15,8 %) and two to the group with open laparotomy (7.7 %). General postoperative complications occured in 15 cases (33.3 %), whereby patients of the conventional cholcystectomy group were concerned more often [46.2 % (n = 12) versus 15.8 % (n = 3), P = 0.03]. The number of days spent in hospital after open cholecystectomy was higher (P = 0.01) (11.6 ± 5.6 days in the laparotomy group versus 7.6 ± 5.0 days in the laparoscopy group). The classification as a high-risk patient indicates an elevation of the perioperative rate of complications in laparoscopic and open cholecystectomy, whereby the rate of postoperative complications is lower in the laparoscopic group.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Der Chirurg 69 (1998), S. 1035-1044 
    ISSN: 1433-0385
    Schlagwort(e): Key words: Ileoanal Pouch ; Redo-Operation ; Complications ; Pouchitis. ; Schlüsselwörter: Ileoanaler Pouch ; Redo-Operationen ; Komplikationen ; Pouchitis.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Die Komplikationsrate nach ileoanaler Pouchrekonstruktion wird in der Literatur mit bis zu 60 % angegeben. Diese Rate beinhaltet allerdings auch postoperative Komplikationen – wie z. B. Ileus, Narbenbruch –, die nach jedem Eingriff auftreten können. Betrachtet man ausschließlich die Pouch-bezogene, also die das Verfahren betreffende Komplikationsrate, so werden zwischen 15 und 25 % angegeben. Dabei zeigen sich als Hauptrisikofaktoren eine erhöhte Spannung der ileoanalen Anastomose, Anastomoseninsuffizienz, ein fehlender Stomaschutz, ein präoperativ undiagnostizierter Morbus Crohn und die Unerfahrenheit des Chirurgen. Wir klassifizierten die Pouchkomplikationen in 5 Kategorien: 1. chirurgische Komplikationen (Anastomoseninsuffizienz, Blutung, pelvine Sepsis, Fisteln), 2. technische Probleme (langer S-Pouch-Auslaß, Rectum-Cuff-Stenose, Pouchsteg), 3. funktionelle Probleme (Analsphincterinsuffizienz, Nachtinkontinenz, hypermotiler Pouch, Evakuationsstörungen), 4. Pouchitis und 5. Pouchneoplasien. Die Pathogenese, Diagnostik und medikamentöse und chirurgische Therapie wird eingehend analysiert. In einer eigenen Serie von 11 Pouch-Redo-Operationen wurde bei 6 Pouchfisteln (3mal mit Morbus Crohn), 3 Fehlkonstruktionen, einem langen S-Pouch-Auslaß sowie einer chronischen Pouchitis in 6 Fällen ein langfristiger Erhalt erreicht. In 3 Fällen mußte der Pouch komplett exstirpiert werden, in 2 Fällen persistierte das Loop-Ileostoma. Aufgrund der technischen Komplexität der Operation, dem nötigen Verständnis der Pathophysiologie sowie der Verfügbarkeit und Beherrschung der nötigen Diagnostik sollte diese Operation nur in darauf spezialisierten Zentren vorgenommen werden.
    Notizen: Summary. The overall rate of complications after ileal pouch–anal anastomosis is 60 %. This rate, however, includes complications such as bowel-obstruction and hernias. Pouch-related complications occur after ileal pouch–anal anastomosis with a frequency of 15–25 %. In an analysis of the recent literature the main risk factors are: tension of the ileal pouch–anal anastomosis, anastomotic leakage, lack of protective ileostomy, preoperatively undiagnosed Crohn's disease and the experience of the surgeon. We classified pouch related-complications into (1) surgical complications (leakage, bleeding, pelvic sepsis, fistulas); (2) technical problems (long S-pouch spout, rectal cuff stenosis, etc.); (3) functional problems (anal sphincter insufficiency, night incontinence, hypermotility, evacuation disorders); (4) pouchitis; (5) pouch neoplasias. Pathogenesis, diagnostic features, and medical and surgical therapy are discussed in detail. In our own series of 11 pouch-redo operations we had 6 pouch fistulas (3 related to Crohn's disease, 3 postoperative fistulas), 3 wrongly constructed pouches, 1 chronic pouchitis and 1 long S-pouch spout. In 3 cases the pouch had to be excised completely. Two patients remained with a permanent ileostomy. In 6 patients the pouch could be preserved on long term. Due to the technical complexity, the need to understand pathophysiology and the need for a differentiated diagnostic procedure, this operation should be performed only in specialised centers.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Der Chirurg 69 (1998), S. 418-422 
    ISSN: 1433-0385
    Schlagwort(e): Key words: Percutaneous dilatational tracheostomy ; Translaryngeal tracheostomy ; Complications ; Results ; Minimally invasive surgery. ; Schlüsselwörter: Punktionstracheostomie ; translaryngeale Tracheostomie ; Komplikationen ; Ergebnisse ; minimal-invasive Chirurgie.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Die Punktionstracheostomie (PT) und die translaryngeale Tracheostomie (TLT) sind relativ neuartige, minimal-invasive Methoden zur Behandlung von langzeitbeatmeten Intensivpatienten. Beide Verfahren werden erstmals innerhalb einer prospektiv-randomisierten Studie an 50 Intensivpatienten (34 m., 16 w., Alter: 18–84 Jahre) hinsichtlich ihrer Frühkomplikationsrate und der perioperativen methodenbedingten Beeinträchtigung der Beatmung verglichen. Bei je 25 Patienten wurde eine PT bzw. eine TLT durchgeführt. Perioperativ wurde in beiden Gruppen keine Hypoxie beobachtet, allerdings war ein Abfall des PaO2 um mehr als 50 mm Hg während der TLT 9mal, bei der PT nur 3mal festzustellen (p = 0,051). Außerdem war der mittlere Anstieg des PaCO2 in der TLT-Gruppe signifikant höher (5,2 ± 6,7 vs. 11,6 ± 8,4 mm Hg; p 〈 0,01). In der PT-Gruppe kam perioperativ keine Komplikation vor, nach TLT mußte einmal zur PT konvertiert werden, nachdem die Kanülenspitze disloziert war. Postoperativ trat einmal eine vorzeitige akzidentelle Dekanülierung nach PT und eine Blutung nach TLT auf. PT und TLT sind bei entsprechender klinischer Erfahrung sichere Methoden. Da bei der TLT unter Umständen mit einer erheblichen Hyperkapnie und einem Abfall des arteriellen Sauerstoffpartialdruckes zu rechnen ist, sollte dieses Verfahren nur bei Patienten ohne spezielle Risiken angewandt werden.
    Notizen: Summary. Percutaneous dilatational tracheostomy (PT) and translaryngeal tracheostomy (TLT) are relatively new minimally invasive methods for critically ill patients. To compare the perioperative procedural safety we analyzed the severity of perioperative blood gas changes in a prospective randomized clinical study in 50 patients (34 men, 16 women; age 18–84 years). Additionally, early complications were documented. Twenty-five PTs and 25 TLTs were performed under tracheoscopic guidance. Perioperative hypoxia did not occur in either group; however, a decrease of PaO2 of more than 50 mm Hg was noticed in nine patients during TLT versus three patients with PT (P = 0.051). The mean increase of PaCO2 was significantly higher in the TLT-group (5.2 ± 6.7 vs 11.6 ± 8.4 mm Hg; P 〈 0.01). In the PT group no perioperative complications arose; in the TLT group one procedure was not successful and had to be converted to a PT. Postoperatively, one premature decannulation (PT group) and one bleeding (TLT group) were noticed. PT and TLT are safe methods. Early complications are rare in experienced hands. TLT tends to cause relevant hypercarbia and should therefore be restricted to patients without special risks.
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Der Chirurg 69 (1998), S. 604-612 
    ISSN: 1433-0385
    Schlagwort(e): Key words: Laparoscopy ; Retroperitoneoscopy ; Nephrectomy ; Complications ; Reintervention ; Conversion. ; Schlüsselwörter: Laparoskopie ; Retroperitoneoskopie ; Nephrektomie ; Komplikationen ; Reintervention ; Konversion.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Der retroperitoneale Zugang findet breite Anwendung bei offenen Operationen in der Urologie. Mit Einführung der Ballondissektionstechnik konnte dieser anatomische Zugang auch für laparoskopische Operationen genutzt werden. Material und Methode: Zwischen 12/1992 und 10/1997 wurden 200 retroperitoneale Operationen an 197 Patienten (Alter 4–82 Jahre) durchgeführt: 78 Nephrektomien, 50 Nierencystenresektionen, 14 Nephropexien, 11 Ureterolysen, 8 retroperitoneale Lymphadenektomien, 8 Nierenbiopsien, 6 Adrenalektomien, 6 Heminephrektomien, 6 Pyeloplastiken, 5 Ureterolithotomien, 6 Ureterocutaneostomien sowie 2 andere. 38 Patienten (19 %) waren bereits abdominell , 22 (11 %) an Niere und Ureter voroperiert. Die Präparation des Retroperitonealraums erfolgte in 14 Fällen mit Hilfe eines Ballonkatheters, in 93 Fällen mittels eines Ballontrokarsystems, während in den letzten 93 Fällen eine Präparation des Retroperitoneums mit dem Zeigefinger sich als ausreichend erwies. Ergebnisse: Die Eingriffe wurden wie folgt klassifiziert: 76 einfache Operationen (z. B. Nierenbiopsie, Nierencystenresektion, Ureterocutaneostomie), 102 schwierige (z. B. Adrenalektomie, Nephrektomie, Nephropexie) und 22 sehr schwierige Eingriffe (z. B. Pyeloplastik, Heminephrektomie, Lymphadenektomie). Während der ersten 50 Fälle zeigte sich eine signifikante Lernkurve, welche sich in einer höheren Operationszeit und Komplikations- sowie Konversionsrate widerspiegelte. Abhängig vom Schwierigkeitsgrad des Eingriffs betrugen die mittlere Operationszeiten 45–100 min bei leichten Eingriffen, 95–185 min bei schwierigen und 185–240 min bei sehr schwierigen Operationen. In den letzten 50 Fällen war die Komplikations-, Konversions- sowie Reinterventionsrate mit offenen Eingriffen vergleichbar (2, 4 und 2 %). Schlußfolgerung: Nach mehr als 200 retroperitoneoskopischen Eingriffen wurde die Zugangstechnik bedeutend vereinfacht, so daß das Verfahren heute standardisiert, sicher und reproduzierbar ist.
    Notizen: Summary. A retroperitoneal access is most commonly applied for open procedures in urology. With introduction of the balloon dissecting technique, this anatomical route could also be used for laparoscopic surgery. Materials and Methods: From 12/1992 to 10/1997, a total of 200 retroperitoneoscopic procedures have been performed in 197 patients (age 4–82 years): 78 nephrectomies, 50 renal cyst resections, 14 nephropexies, 11 ureterolyses, 8 retroperitoneal lymph-node dissections, 8 renal biopsies, 6 adrenalectomies, 6 heminephrectomies, 6 pyeloplasties, 5 ureterolithotomies, 6 ureterocutaneostomies and 2 others. Thirty-eight patients (19 %) had undergone previous abdominal surgery; 22 (11 %) had had kidney and ureter operations. Dissection of the retroperitoneal space was done with a balloon catheter in 14 or a balloon trocar system in 93 cases, and in the last 93 patients digital dissection with the index finger proved to be sufficient. Results: We classified 76 as simple (i. e., renal biopsy, renal cyst resections, ureterocutaneostomy) and 102 as difficult (i.e. adrenalectomy, nephrectomy, nephropexy) and 22 (11 %) as very difficult operations (i. e., pyeloplasty, heminephrectomy, lymphadenectomy). There has been a significant learning curve during the first 50 cases as reflected by increased operating time and complications and the conversion rate to open surgery. After that, the OR times mainly depended on the difficulty of the procedure, averaging 45–100 min for an easy retroperitoneoscopy, 95–185 min for a difficult and 185–240 min for a very difficult operation. In the last 50 cases, the complications, conversion and reintervention rate have become comparable to open surgery (2, 4 and 2 %). Conclusions: After more than 200 cases of retroperitoneoscopy, the access technique has been significantly simplified. The procedure is standardized, safe and reproducible.
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  • 19
    ISSN: 1433-0385
    Schlagwort(e): Key words: Hernia inguinalis ; Laparoscopic hernioplasty ; Complications ; Recurrences ; Learning curve. ; Schlüsselwörter: Leistenbruch ; laparoskopische Hernioplastik ; Komplikationen ; Rezidive ; Lernkurve.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. In der vorliegenden Studie werden erstmals an einem sehr großen Krankengut von 3400 Hernienreparationen prospektiv Risiko, Nutzen und Kosten der laparoskopischen Hernioplastik in der transabdominellen Technik mit präperitonealer Plazierung eines Polypropylennetzes untersucht. Die medianen Operationszeiten betrugen für die einseitige Primärhernie 45 min, für die einseitige Rezidivhernie 50 min und für die doppelseitige Hernie 76 min. Die Komplikationsfrequenz zeigte eine signifikante Abhängigkeit von den einzelnen Schritten der Methodenentwicklung sowie der individuellen Lernkurve. Das gleiche gilt für die Rezidivrate. Während anfänglich die Rate größerer Komplikationen bei 2,75 %, bei den kleineren Komplikationen bei 11 % und die Rezidivrate bei 4,5 % lag, betragen die entsprechenden Zahlen aktuell 0,4 %, 4,4 % bzw. 0,5 %. Die laparoskopische Hernioplastik erwies sich als gleich effektiv in der Behandlung der Primärhernie, der Rezidivhernie und der doppelseitigen Hernie. Die große Zahl von insgesamt 11 Operateuren zeigt, daß die laparoskopische Hernioplastik erlernbar ist und auch in einer Ausbildungsklinik sicher, effizient und kosteneffektiv durchgeführt werden kann.
    Notizen: Summary. In the present study, for the first time the aspects of risk, benefit and the costs of laparoscopic hernioplasty in the transabdominal technique with preperitoneal placement of a polypropylene mesh are examined prospectively in a very large group of patients with 3,400 hernia repairs. The median operation time was 45 min for unilateral primary hernias, 50 min for unilateral recurrent hernias and 76 min for bilateral hernias. The frequency of complications showed a significant dependence on the individual steps in the development of the method and the individual learning curve. The same is true for the rate of recurrency. Whereas initially the rate of serious complications was 2.75 %, the rate of minor complications 11 % and the rate of recurrences 4.5 % the corresponding figures are at present 0.4 %, 4.4 % and 0.5 %. Laparoscopic hernioplasty proved to be equally as effective in the treatment of primary hernias, recurrent hernias and bilateral hernias. The large number of 11 surgeons participating proves that laparoscopic hernioplasty can be learned and that even in a teaching hospital it can be performed safely, efficiently and cost-effectively.
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  • 20
    ISSN: 1433-0458
    Schlagwort(e): Schlüsselwörter Kopf-Hals-Tumoren ; PEG ; Komplikationen ; Langzeiternährung ; Key words Head and neck cancer ; PEG ; Complications ; Long-term nutrition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Percutaneous endoscopically controlled gastrostomy (PEG) enables patients suffering from a tumor of the upper aerodigestive tract to receive direct gastric feedings. The procedure also avoids the social stigma of a nasal feeding tube. The results of 630 PEG procedures used in 555 patients suffering from various head and neck cancers are reported. The mean age of the patients was 58.0 years with a range from 11 to 92 years. The PEG procedure was carried out under local anesthesia in 60% of the cases and with general anesthesia in 40%. In 512 patients the initial PEG procedure was successful while 43 of the patients required a second PEG procedure after loss of the PEG. In 19 patients the PEG procedure was not successful because of tumor obstruction or it was not possible to perform endoscopy. Twenty-four patients were successfully treated in a second or third session. Altogether 97% (n = 563) of all 555 patients and 92% (n = 579) of all PEG procedures were successful. The mean duration of PEG use was 243 days (range: 0–2271 days). In 66 patients (10.5%) complications occurred but severe complications developed in only 8 patients (1.3%). Operative interventions were necessary in two cases. No deaths resulted from the PEG. These findings show that the PEG technique is safe to do with only few complications when performed by a skilled team.
    Notizen: Zusammenfassung Die perkutane endoskopisch kontrollierte Gastrostomie (PEG) emöglicht Patienten mit Tumoren des oberen Aerodigestivtraktes eine direkte intragastrale Ernährung unter Ausschaltung der sowohl durch den Tumor selbst als auch die Tumortherapie stark alterierten Schluckstraße und erspart ihnen die soziale Stigmatisierung durch eine Nasensonde. Die Ergebnisse von 630 PEG-Prozeduren bei 555 Patienten mit Kopf-Hals-Tumoren werden vorgestellt. Die Patienten waren zum Zeitpunkt der PEG-Anlage im Durchschnitt 58,0 (11–92) Jahre alt. Der Eingriff erfolgte in 60% in Lokalanästhesie, in 40% in Intubationsnarkose. 512 Patienten wurden primär erfolgreich mit einer PEG versorgt. Von diesen 512 Patienten unterzogen sich 43 Patienten im Beobachtungszeitraum erneut einer erfolgreichen PEG-Prozedur nach Sondenverlust. Bei 19 Patienten war die Anlage einer PEG wegen endoskopisch – auch nach Bougierungsbehandlung – nicht passierbarer Tumorobstruktion oder fehlender Darstellbarkeit der Diaphanoskopie nicht möglich. Weitere 24 Patienten wurden nach zunächst erfolglosen Versuchen mit einer PEG versorgt. Somit war bei 97% (n = 536) der 555 Patienten bzw. bei 92% (n = 579) der 630 PEG-Prozeduren die PEG-Anlage erfolgreich. Bei einer mittleren Sondentragedauer von 243 (Spanne 0–2271) Tagen beobachteten wir bei insgesamt 10,5% (n = 66) der PEG-Anlagen Komplikationen, davon in nur 1,3% (n = 8) schwere Komplikationen; lediglich bei zwei Patienten war eine operative Intervention notwendig. Durch die Methode bedingte Todesfälle ereigneten sich nicht. Die Technik der PEG erweist sich damit in den Händen des erfahrenen Endoskopikers als sicher, komplikationsarm und den Patienten wenig belastend.
    Materialart: Digitale Medien
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  • 21
    ISSN: 1433-0407
    Schlagwort(e): Schlüsselwörter Fibrinolyse ; Intrazerebrale Blutung ; CT ; Kontrastmittel ; Komplikation ; Key words Fibrinolysis ; Cerebral hemorrhage ; Computed tomography ; Contrast medium ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary
    Notizen: Zusammenfassung
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    International journal of legal medicine 111 (1998), S. 154-156 
    ISSN: 1437-1596
    Schlagwort(e): Key words Air embolism ; Gastroscopy ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Rechtswissenschaft
    Notizen: Abstract Although venous air embolism is a known complication in medical practice in general, only a single case of upper gastrointestinal endoscopy complicated by venous air embolism with consecutive acute cardiovascular failure has so far been described in literature. Here we show that gastroscopy may be accompanied by massive, i.e. fatal venous air embolism. If a vessel in the gastrointestinal tract is exposed but does not collapse (in the case of a gastric ulcer, for example) air insufflated under pressure by the gastroscope may lead to a fatal air embolism. Our tests using a commercial gastroscope revealed that an overpressure of up to 43 kPa (kiloPascals) is reached without the rinsing function while an overpressure of up to 45 kPa is measured if the rinsing function is operated simultaneously. The maximum flow rates without resistance were 100 ml/min for rinsing liquid (purified water) and 2000 ml/min for air. Our results suggest that air insufflation by the gastroscope may result in a critical air embolism within very few seconds on condition that a connection with the vascular system exists. However, this complication is extremely rarely encountered. We propose that CO2 should be administered in place of air or alternatively the maximum pressure should be considerably reduced to avoid a fatal outcome in routinely performed gastroscopical examinations.
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  • 23
    ISSN: 1437-9813
    Schlagwort(e): Key words Esophageal atresia ; Tracheoesophageal fistula ; Prognosis ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The management of esophageal atresia (EA) and tracheoesophageal fistula (TEF) has improved markedly over the years, with a current overall survival of 80%–90%. This however, is not the case in developing countries, where mortality continues to be high. The results of treatment of 41 consecutive cases EA and/or TEF have been analyzed to determine factors pertinent to the outcome. The distribution of anomalies and a postoperative survival of 86.8% were comparable to those from developed countries. Aspiration pneumonia was unusually frequent in our patients (78%), but did not adversely influence outcome. Associated congenital anomalies as well as low birth weight continue to be important predictors of outcome in our setting. Our post-operative complications were similar to those from developed countries apart from a high incidence of stricture formation. This was attributed to gastroesophageal reflux, non-ventilation post-operatively, and the use of silk sutures to construct the anastomosis.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Skeletal radiology 27 (1998), S. 427-433 
    ISSN: 1432-2161
    Schlagwort(e): Key words Osteochondroma ; Complications ; MR imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Objective. To demonstrate the value of MR imaging in the diagnosis and differentiation of the various symptomatic complications of osteochondromas, providing pathological correlation with emphasis on the usefulness of MR imaging as a single imaging modality in these patients. Design. We retrospectively reviewed all MR examinations of clinically symptomatic osteochondromas (30 patients) performed at our institution between March 1990 and October 1997. Patients. Thirty patients had clinically symptomatic osteochondromas during the study period. Twenty patients were male and 10 were female. There were five cases of multiple osteochondromatosis. Pathological correlation was available in 24 patients. Results and conclusion . Symptomatic complications included fracture (7%), osseous deformity limiting range of motion (23%), vascular injury (7%), neurological compromise (10%), bursa formation (27%) and malignant transformation (27%). MR imaging was able to diagnose or suggest the etiology for the clinical symptomatology in all cases, demonstrating that it is an ideal imaging modality in the diagnostic evaluation of symptomatic complications of osteochondromas and often avoids the need for further imaging.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    European journal of pediatrics 157 (1998), S. 666-672 
    ISSN: 1432-1076
    Schlagwort(e): Key words Multicystic dysplastic kidney ; Complications ; Nephrectomy ; Renal function ; Contralateral anomalies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A clinical study of 204 patients with unilateral multicystic renal dysplasia referred to 30 nephrology departments was undertaken to assess the frequency of complications in children who underwent nephrectomy (n=40) versus those who were treated conservatively (n=164). Six patients required antihypertensive treatment, 30 (13% of girls, 17% of boys) had at least one episode of urinary tract infection. The number of clinical complications did not differ in patients who underwent nephrectomy in comparison to those who did not. The dysplastic kidney decreased in size in 65% of kidneys with repeated ultrasound values; no change occurred in 16%, while an increase in maximal diameter was observed in 19%. Contralateral kidney length of more than 2 standard deviation scores (SDS) was seen in 30% of patients. There is evidence for a slight impairment of renal function in the whole study group given by a median of serum creatinine level of 0.63 SDS in all patients available for analysis. Among those 35 patients with contralateral anomalies (mainly obstructive changes and vesico-ureteral reflux), all 3 patients with contralateral changes suggestive of hypoplasia and 22% with obstruction, but only 1/7 (14%) with reflux showed elevated serum creatinine level 〉2 SDS. Conclusion Renal function seems to be slightly impaired in patients with unilateral multicystic renal dysplasia. The apparent tendency to regression of the dysplastic kidney and no difference in the number of complications justify a conservative management rather than operative intervention.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Intensive care medicine 24 (1998), S. 194-196 
    ISSN: 1432-1238
    Schlagwort(e): Key words Horner's syndrome ; Internal jugular vein ; Cannulation ; Pulmonary artery ; Catheterization ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We present two cases of Horner's syndrome occurring following uncomplicated internal jugular venous cannulation. An awareness of this potential complication will reduce confusion over the aetiology of anisocoria in critically ill patients. This consideration is important, since lesions in the central nervous system or carotid dissection following trauma might otherwise be suspected.
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  • 27
    ISSN: 1432-1238
    Schlagwort(e): Key words Percutaneous dilatational tracheostomy ; Complications ; Results ; Tracheal stenosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective: To analyze perioperative and postoperative complications and long-term sequelae following percutaneous dilatational tracheostomy (PDT). Design: A prospective clinical study of patients undergoing PDT. Setting: Seven intensive care units at a University hospital Patients: 326 intensive care patients (202 male, 124 female; age: 11–95 years) with indications for tracheostomy. Interventions: Using tracheoscopic guidance, 337 PDTs were performed according to Ciaglias' method. In 106 decannulated patients, tracheal narrowing was assessed by plain tracheal radiography. Results: Two procedure-related deaths were seen (0.6 %). Perioperative and postoperative complications occurred with 9.5 % of the PDTs. One of 106 patients, who were followed-up for at least 6 months, showed a clinically relevant tracheal stenosis. Subclinical tracheal stenosis of at least 10 % of the cross-sectioned area was recognized in 46 of 106 patients (43.4 %). In the univariate analysis, the degree of stenosis was influenced by the age of the patient (p = 0.044), the duration of intubation prior to PDT (p = 0.042) and by the duration of cannulation (p = 0.006). These parameters had no statistical significance in a multiple regression model. Conclusion: When performed by experienced physicians, percutaneous dilatational tracheostomy under fiberoptic guidance is a safe method. The risks of early complications and of clinically relevant tracheal stenoses are low. Subclinical tracheal stenoses are found in about 40 % of patients following PDT.
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  • 28
    ISSN: 1432-198X
    Schlagwort(e): Key words: Outpatient ; Percutaneous renal biopsy ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Although several retrospective reports suggest that pediatric outpatient renal biopsies may be done in a safe and cost-effective manner, risk factors and the natural history of major complications following this procedure have not been clearly delineated. In an effort to determine the minimal observation period required to detect major post-renal biopsy complications in children and to establish clinical parameters predictive of these complications, a retrospective review of 177 percutaneous renal biopsies was performed. The overall major complication rate was 3.4%, while the minor complication rate was 14.1%. The mean percentage change in hemoglobin 4 – 10 h postbiopsy in patients with major bleeding complications was significantly greater than patients with minor bleeding complications. Using a 16% drop in hemoglobin 4 – 10 h postbiopsy, the sensitivity and specificity of identifying a major bleeding complication was 100% and 98%, respectively, while the positive and negative predictive value was 68% and 100%, respectively. All patients with major complications due to excess sedation or immediate bleeding were diagnosed within 11 h of the biopsy. Automated renal biopsies offered several safety and efficiency advantages compared with non-automated methods. Our results suggest that outpatient pediatric renal biopsies should be encouraged provided certain precautions are taken to reduce the risk of developing major complications.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 8 (1998), S. 371-376 
    ISSN: 1432-1084
    Schlagwort(e): Key words: MR mammography ; Breast ; Implants ; Augmentation ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Mammographic evaluation of the augmented breast is challenging, since breast implants obscure significant amount of breast tissue while diminishing the effect of compression. Posttherapeutic scarring can make mammographic interpretation even more difficult. MRI has thus evolved into the modality of choice for diagnosing implant complications as well as detection of primary or recurrent breast cancer in these patient population. The present article attemps to give an overview of the MR findings of different breast augmentation and reconstruction techniques, i. e. prosthetic breast implants, breast reconstruction with autogenous tissue, free silicone injections and fat grafts, and their complications.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    European spine journal 7 (1998), S. 104-110 
    ISSN: 1432-0932
    Schlagwort(e): Key words Ankylosing spondylitis ; Osteotomies ; Lumbar spine ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Between 1984 and 1993 we treated 21 consecutive patients who had progressive thoracic kyphosis due to ankylosing spondylitis by polysegmental posterior lumbar wedge osteotomies. In 19 patients we used the Universal Spinal Instrumentation System and in the last 2 patients the H-frame. The average correction in 20 of 21 patients at follow-up was 25.6° (range 0°–52°), with a mean segmental correction of 9.5° and a mean loss of correction after operation of 10.7° (range 0°–36°). There were no fatal complications, but in one patient no correction could be obtained during surgery and another patient was reoperated due to lack of correction. Breaking out of screws through the pedicle during compressive correction was seen in seven patients. Implant failure, such as breakage of the threaded rods and/or loosening of the junction between the pedicle screw and the rod, occurred in 9 out of 21 patients. Two patients required reoperation at long-term follow-up. Five out of seven deep wound infections required removal of the implant. Polysegmental lumbar wedge osteotomies for correction of progressive thoracic kyphosis in ankylosing spondylitis is only recommended in patients at a mild stage of the disease with mobile discs and in combination with strong instrumentation.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    European spine journal 7 (1998), S. 438-444 
    ISSN: 1432-0932
    Schlagwort(e): Key words Vertebral metastases ; Complications ; MRI
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The authors report their experience concerning complications of spinal metastasis surgery. The purpose of this study was to assess the frequency of such complications and analyse the factors influencing their occurrence. The records of 145 patients treated between 1982 and 1991 for metastatic disease of the spine were retrospectively reviewed for intra- and postoperative complications. Other factors such as radiation therapy, emergent nature of surgery, and neurologic deficits were analysed for potential correlations with the frequency of complications. Twenty-seven (18.6%) patients developed postoperative complications. Wound dehiscence and infection (11%) were the most frequent complications. Statistical analysis showed a significant influence of three factors: preoperative radiation therapy, paraplegia before surgery, and surgery under emergency conditions. The rate of complications in this surgery is lower than might be expected and can be significantly reduced. Surgery should be performed before radiation therapy and before appearance of substantial neurologic deficits.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    European journal of trauma 24 (1998), S. 162-169 
    ISSN: 1615-3146
    Schlagwort(e): Retrograde Marknagelungstechnik ; Distale und supra/diakondyläre Femurfrakturen ; Komplikationen ; Retrograde nailing technique ; Distal and supra/diacondylar femoral fractures ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract We performed retrograde femoral nailing in 20 patients with 20 fractures of the distal femoral region. All fractures were stabilized on the day of admission after performing closed reduction. There were 15 distal femoral or supra/diacondylar fractures type A and 5 type C fractures. Four fractures were classified open (3A). Eight patients had previous surgery with implanted hip arthroplasties or dynamic hip screws. Immediate passive motion and mobilisation were begun postoperatively. All fractures healed. Follow-up was 27 months after surgery (range: 20 to 33 months). There were neither failure of the implant nor infections. In 4 patients we had loosening of interlocking screws but only 1 had to be reoperated. Two implants were chosen too long and had to be exchanged. Functional results were assessed based on the score of Leung et al. [11]. Six patients showed an excellent result, 4 a good, 3 a fair and 1 patient a poor result. We conclude retrograde interlocking femoral nailing has proven to be a minimal invasive stabilisation method for closed and open supra/diacondylar and distal femoral fractures. As there is the possibility of technical pitfalls, this technique should only be performed by well trained surgeons.
    Notizen: Zusammenfassung Unsere ersten 20 mit einem retrograden Femurmarknagel versorgten Patienten wurden 27 Monate postoperativ (20 bis 33 Monate) nachuntersucht. Alle Patienten waren am Unfalltag in geschlossener Operationsweise behandelt worden. Nach der AO-Klassifikation handelte es sich um 15 distale oder supra/diakondyläre Typ-A-Frakturen und fünf Typ-C-Frakturen. Darunter waren vier offene Frakturen vom Typ 3A nach Gustilo. Bei acht Patienten waren auf der zu operierenden Seite bereits von früheren Verletzungen dynamische Hüftschrauben oder Endoprothesen implantiert. Postoperative wurden die Patienten sehr rasch ohne weitere Fixation mobilisiert. Alle Frakturen waren primär geheilt. Wir verzeichneten keinen Implantatbruch und keine Infektion. Bei vier Patienten kam es zur Lockerung von Verriegelungsbolzen, wovon ein Patient wegen der resultierenden Frakturinstabilität revidiert werden mußte. Bei zwei Pateinten wurde ein zu langer Nagel implantiert und dieser dann bei der Revisionsoperation durch einen kürzeren Nagel ersetzt. Die funktionellen Resultate wurden bei der Nachuntersuchung nach dem Score von Leung et al. [11] bewertet. Sechs Patienten zeigten exzellente Ergebnisse, vier Patienten gute, drei mäßige und ein Patient ein schlechtes Ergebnis. Nach unseren ersten Erfahrungen ist die retrograde Marknagelung von distalen Femurfrakturen eine ausgezeichnete Technik zur Frakturstabilisation sowohl von geschlossenen und offenen distalen als auch supra/diakondylären Femurfrakturen. Zudem handelt es sich um eine minimal-invasive Methode mit den sich daraus ergebenden Vorteilen. Da die Technik jedoch sehr anspruchsvoll ist, sollte sie nur von adäquat ausgebildeten und geübten Unfallchirurgen vorgenommen werden.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Arthroskopie 11 (1998), S. 98-101 
    ISSN: 1434-3924
    Schlagwort(e): Schlüsselwörter Ambulante Operationen ; Voraussetzungen ; Eigenes Procedere ; Postoperatives Management ; 4588 ambulante op. Eingriffe ; Komplikationen ; Akzeptanz ; Ausschlußkriterien ; Key words Outpatient operations ; Requirements ; Individual procedure ; Postoperative management ; 4588 outpatient operations ; Complications ; Aceptance ; Exclusion criteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: This study describes the approach that is necessary in outpatient surgery in order to carry out the operation safely. The particular procedure is discussed, and the necessity of strict postoperative management is shown. Between 1994 and 1997, the author supervised 4588 outpatient operations, of which 3020 were arthroscopic. The observed complications are listed and evaluated. Overall, outpatient surgery is well accepted by the patients. The criteria for denying a patient surgery on an outpatient basis are laid out.
    Notizen: Die Arbeit schildert die Voraussetzungen, die zum ambulanten Operieren notwendig sind, um die Eingriffe sicher gestalten zu können. Das eigene Procedere des Behandlungsablaufes wird geschildert. Die Notwendigkeit eines strengen postoperativen Managementes wird dargelegt. Von 1994 bis 1997 überblicken die Autoren 4588 ambulante operative Eingriffe, davon 3020 ambulante arthroskopische Operationen. Die beobachteten Komplikationen werden aufgelistet. Insgesamt wird das ambulante Operieren vom Patienten akzeptiert. Ausschlußkriterien zum ambulanten Operieren werden aufgestellt.
    Materialart: Digitale Medien
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  • 34
    ISSN: 1433-0385
    Schlagwort(e): Key words: Gastric banding ; Complications ; Therapy. ; Schlüsselwörter:„Gastric banding“ ; Komplikationen ; Therapie.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Das laparoskopische „gastric banding“ hat sich zu einem etablierten Verfahren in der Chirurgie der Fettsucht entwickelt. Früh- und Spätkomplikationen sind im Vergleich zu herkömmlichen Verfahren seltener. Operationstechnisch bedingte Komplikationen sind die Magenperforation, die frühe Pouchdilatation, das Magen-slipping, Infektionen des Implantats, die Bandarrosion und Defekte des Band- und Schlauchsystems. Eine unzureichende Gewichtsabnahme und die späte Pouchdilatation sind durch die unzureichende Compliance des Patienten verursacht. In 7,5 % von 146 Patienten waren Wiedereingriffe notwendig. Erbrechen und die Unfähigkeit der Flüssigkeitszufuhr sind Symptome einer Stomaocclusion oder eines „slipping“. Die sofortige Röntgendiagnostik mit anschließender „Entblockung des Systems“ ist notfallmäßig vorzunehmen. Bei einer Pouchdilatation oder einem „slipping“ wird eine Magensonde in den Pouch plaziert. Läßt sich durch diese Maßnahmen keine Passage wiederherstellen, muß notfallmäßig die operative Korrektur erfolgen.
    Notizen: Summary. Laparoscopic gastric banding has become a common procedure in bariatric surgery. Early as well as late complications are, in comparison to conventional techniques, rare. Complications arising from the operative technique are: perforation, early pouch dilatation, gastric slippage, infections of the port and the band, erosion and defects of the band tube. Insufficient weight loss and late pouch dilatation arise from unsatisfactory compliance on the part of the patient. In 7.5 % of 146 cases, reoperations were necessary. Obstruction of the pouch stoma and a slippage resulted in total food intolerance. After radiologic diagnosis the band system should be deflated first and a naso-gastric tube applied. If this does not result in the pouch collapsing, a revision operation is needed.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    European journal of plastic surgery 21 (1998), S. 106-107 
    ISSN: 1435-0130
    Schlagwort(e): Key words Fingertip injury ; Nail bed ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We report the long term sequel of a finger tip injury (case report). Attention to detail, particularly in repairing the nail bed and a decision at the time to either retain and repair, or excise fully, the germinal matrix could avoid long term complications.
    Materialart: Digitale Medien
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  • 36
    ISSN: 1434-9949
    Schlagwort(e): Chronic pancreatitis ; Complications ; Pseudocyst
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe two patients with pancreatitis. One patient had acute pancreatitis of biliary origin and presented with small joint polyarthritis and panniculitis lesions. The other patient was originally hospitalised for dyspnoea with bilateral pleural effusion, and subsequently developed migratory polyarthritis. During his hospital stay he developed panniculitis lesions and a monoclonal IgG disorder of unknown significance. Very few patients with pancreatitis develop polyarthritis and panniculitis. The appearance of pseudocysts in the pleural and mediastinal cavity in the course of pancreatitis is an infrequent complication.
    Materialart: Digitale Medien
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  • 37
    ISSN: 1435-0130
    Schlagwort(e): Key words Radial forearm free flap ; Oral and oropharyngeal cancer ; Squamous cell carcinoma ; Reconstruction ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The success rate of 56 free radial forearm flaps used between 1987 and 1995 in the University Hospital Groningen, The Netherlands for oral and oropharyngeal reconstructions in cancer patients, was evaluated. There were 36 men and 20 women. The most prevalent neoplasm was squamous cell carcinoma (n=52). Most tumours were stage IV (n=33). Oral tumors were most common (n=34), while oropharyngeal tumours were present in 22 patients. In 48 cases a fasciocutaneous flap was used, while an osseofasciocutaneous flap was taken in 8 patients. Recipient-site problems occurred in 31 patients (55%). There was total flap loss in 4 patients (7%) and partial flap loss in 4 (7%). Donor-site complications were seen in 18 patients (32%). Total loss of skin graft occurred in 1 patient (2%) and partial loss of skin grafts in 7 patients (13%). A fracture of the radius was observed in 2 patients. The overall success rate of the radial forearm free flap was 86%. Free vascularised tissue transfer to the oral and oropharyngeal regions should be carried out in a centre with a multidisciplinary head and neck team with experienced microsurgeons.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 255 (1998), S. 124-126 
    ISSN: 1434-4726
    Schlagwort(e): Key words Acoustic neuroma surgery ; Facial palsy ; Complications
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Delayed onset of facial palsy is possibly an underestimated but distressing complication of acoustic neuroma surgery. The incidence of this complication reported in the literature has varied from 11.7 to 41%.This study reviewed retrospectively 60 primary acoustic neuroma surgeries performed by a single neurotologist. The deelayed onset of facial dysfunction was defined according to the guidelines described by of Lalwani Butt, Jackler, Pitts and Jingling in 1995. They considered either a deterioration of facial function from normal to abnormal or an increased severity of the degree of facial paralysis, which was grouped using the House-Brackmann scale system. Fifteen of the 60 patients (25%) were found to have a deterioration of facial function. The incidence of delayed facial palsy was not influenced by age, sex or tumor size. The majority of the patients had a favorable prognosis. Only three patients had a grade III–IV facial function at 1 year. It is possible that these latter cases might have benefited from intraoperative meatal facial nerve decompression, as advocated by Sargent, Kartush and Graham.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 236-250 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: To get informations on both the structure and dynamics of hydrogen chelates 1 of heteroaromatic systems, a great variety of quinazoline-2-acetonitrile chelates were synthesized (see 2-4). Similarly to the situation of the corresponding H-chelates in the pyrimidine-2-acetonitrile series, the investigation of these new derivatives 2-4 by NMR spectroscopic methods (DNMR, COSY, NOESY, ROESY, EXSY, HMQC, HMBC) confirms the presence of an equilibrium of the two possible H-chelate structures (two ‘rotamers’ I and II, i.e., (E)/(Z) isomers; see Scheme). The corresponding equilibria I ⇌ II were determined by complete 1H-NMR signal assignment at low temperatures (after freezing the rotational processes). In addition, the tautomer equilibria A ⇌ B (relative energies of the two minima of the nonsymmetrical double-well potential) for both ‘rotamers’ are ascertained by H,H and C,H couplings. The results are an important basis for the interpretation of both the UV/VIS absorptions and the dependence of fluorescence and fluorescence quantum yields on temperature.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 40
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stereoselective reactions of phthalimido-substituted radicals derived from (±)-threonine with different radical traps are reported (Scheme 3, Table 1). A strong influence of the nature of the radical trap on the stereoselectivity was noticed. Small nucleophilic radical traps gave preferentially the syn products. The observed selectivities are explained with the A1,3 strain model and depend on steric and electronic effects (Fig. 2). Reactions with electrophilic radical traps such as diphenyl diselenide gave the anti diastereoisomers with moderate stereocontrol, presumably due to stereoelectronic effects. The same stereochemical outcome, i.e., preferential formation of the anti products, was observed for the reactions of the related N-phthaloyliminium ion (Scheme 5, Table 2). The stereochemistry of the ionic reaction is rationalized by a Felkin-Anh model (Fig. 3).
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 307-316 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cyclopalladation of 1,1′-azonaphthalene (= di(naphthalen-1-yl)diazene; 2) with bis(hexafluoroacetyl-acetonato)palladium(II) (3; [Pd(hfa)2]) yields the ortho-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)[1-(naphthalen-1-ylazo-κN2)naphthalen-2-yl-κC2]palladium(II) (4) as well as the peri-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)[8-(naphthalen-1-ylazo-κN2)naphthalen-1-yl-κC1]-palladium(II) (5); their structures were corroborated by X-ray analyses. The formation of the novel peri-metallated product 5 containing a six-membered palladacycle strongly depends upon the reaction conditions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 342-352 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photoisomerization behavior of three mono[(E)-3-(4-hydroxyphenyl)prop-2-enoyl]spermidines, 1, 2, and 3, and three bis[(E)-3-(4-hydroxyphenyl)prop-2-enoyl]spermidines, 4, 5, and 6, are investigated. The synthetic product (E)-1 could be almost quantitatively (〉 96%) converted into its isomer (Z)-1 under UV light irradiation. In the cases of (E)-2 and (E)-3, a mixture of (E)/(Z) ca. 1:2 was obtained, when the same conditions were applied. The comparison of their UV spectra provides the possible explanation for these different behaviors. Furthermore, it was noticed that the (Z) → (E) isomerization of the C=C bond took place during the purification by reverse-phase high-performance liquid chromatography (RP-HPLC), and the (E)/(Z)-mixture is thus inseparable. The same feature could be observed during the isolation of the (Z,Z)-N,N′-bis[3-(4-hydroxyphenyl)prop-2-enoyl]-spermidines, (Z,Z)-4, (Z,Z)-5, and (Z,Z)-6. Nevertheless, the fractions of (Z,Z)-5 and (Z,Z)-6 were in almost pure state collected, and their 1-NMR spectra are presented.
    Zusätzliches Material: 5 Ill.
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  • 43
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 153-162 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis, absolute configuration, and olfactive evaluation of (-)-(E)-α-trans-bergamotenone (= (-)-(1′S,6′R,E)-5-(2′,6′-dimethylbicyclo[3.1.1]hept-2′-en-6′-yl)pent-3-en-2-one; (-)-1), as well as its homologue (-)-19 are reperted. The previously arbitrarily attributed absolute configuration of 1 and of (-)-α-trans-bergamotene (= (-)-(1 S,6R)-2,6-dimethyl-6-(4-methylpent-3-enyl)bicyclo[3.1. 1]hept-2-ene; (-)-2), together with those of the structurally related aldehydes (-)-3a,b and alcohols (-)-4a,b, have been rigorously assigned.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 182-186 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (-)-(R)-4,4,4,4′,4′,4′-Hexafluorovaline hydrochloride ((R)-5) of 98% ee is prepared from β,β-bis(trifluoromethyl)acrylic acid (= benzyl 4,4,4-trifluoro-3-(trifluoromethyl)but-2-enoate; 1) in 4 steps with an overall yield of 9.6%. Key step is the separation of the TsOH salts of the diastereoisomers obtained by anti-Michael addition of (+)-(R)-1-phenylethylamine (2) to 1 (→ (R,R)-3). In contrast to the published (S)-chirality, the X-ray structure analysis of (R,S)-6 reveals, that (R)-chirality has to be assigned to the levorotatory (-)-4,4,4,4′,4′,4′-hexafluorovaline hydrochloride.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 207-218 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and characterization of tripodal dodecadentate ligands with salicylamide and bipyridine binding sites for iron(II) and iron(III) are presented.
    Zusätzliches Material: 1 Ill.
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  • 46
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of CuO'Bu with CO2, and iPr2NH in the presence of PPh3, gives the dialkylcarbamato complex [Cu(O2CNiPr2)(PPh3)2] (1). The CO2/R2NH system (R = Me, Et) in an appropriate organic medium reacts with Ag2O giving the corresponding N,N-dialkylcarbamato complexes of analytical formula [Ag(C2CNR2)] (R = Me, 2; R = Et, 3). The methyl derivative 2 was characterized by X-ray diffraction methods. Crystal data of 2: for [Ag2(O2CNMe2)2], C6H12Ag2N2O4, mol. wt. 391.9; monoclinic, space group P21/c, a = 12.08(1), b = 3.797(2), c = 11.316(7) Å, β = 113.37(6)°, V = 476.3 Å3, Z = 2, Dc = 2.732 g cm-3; μ(MoKα) = 40.64 cm-1, F(000) = 376.0; R = 0.059, Rw = 0.067; g.o.f. 1.27. The structure consists of dinuclear [(Ag2OCNMe2)2] units with slightly distorted linearly two-coordinated Ag-atoms containing bridging carbamato groups to form a substantially planar eight-membered ring with an intra-annular Ag—Ag distance of 2.837(2) Å; the dinuclear units are further joined by Ag—O bonds to form an infinite array. Compound 3, which is presumably dinuclear, as suggested by cryoscopic measurements in benzene, undergoes a structural fission with PPh3, giving the mononuclear triphenylphosphine derivative [Ag(O2CNEt2)(PPh3)2] (4). The amine-catalyzed conversion of Ag2O into Ag2CO3, in the presence of the iPr2NH/CO2 system, is also reported. Cl-Exchange from [AuCl(PPh3)] with [Ag(O2CNEt2)] (3) gives the first N,N-dialkylcarbamato complex of gold, namely [Au(O2CNEt2)(PPh3)] (5), which crystallizes in the monoclinic system: C23H25AuNO2P · 0.5 C7H16, mol. wt. 625.5, space group P21/c; a = 13.212(5), b = 12.25(1), c = 16.795(6) Å, β = 109.09(2)°, V = 2568(2) Å3, Z = 4, Dc, = 1.618 g cm-3; μ(AgKα) = 31.40 cm-1, F(000) = 1236.0; R = 0.058; Rw = 0.064; g.o.f. 2.121. The compound contains two-coordinated Au-atom, namely to the P-atom and to the O-atom of the monodentate carbamato group, the P—Au—O bond angle being 174.7(3)°. The reaction with MeI showed these compounds to react predominantly at the carbamato O-atom giving the corresponding urethanes R2NCO2Me. Evidence was gathered for the transient coordination of CO to Ag in 3.
    Zusätzliches Material: 2 Ill.
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  • 47
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 285-302 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reactions of α-diazo ketones 1a,b with 9H-fluorene-9-thione (2f) in THF at room temperature yielded the symmetrical 1,3-dithiolanes 7a,b, whereas 1b and 2,2,4,4-tetramethylcyclobutane-1,3-dithione (2d) in THF at 60° led to a mixture of two stereoisomeric 1,3-oxathiole derivatives cis- and trans-9a (Scheme 2). With 2-diazo-1,2-diphenylethanone (1c), thio ketones 2a-d as well as 1,3-thiazole-5(4H)-thione 2g reacted to give 1,3-oxathiole derivatives exclusively (Schemes 3 and 4). As the reactions with 1c were more sluggish than those with 1a,b, they were catalyzed either by the addition of LiClO4 or by Rh2(OAc)4. In the case of 2d in THF/LiClO4 at room temperature, a mixture of the monoadduct 4d and the stereoisomeric bis-adducts cis- and trans-9b was formed. Monoadduct 4d could be transformed to cis- and trans-9b by treatment with 1c in the presence of Rh2(OAc)4 (Scheme 4). Xanthione (2e) and 1c in THF at room temperature reacted only when catalyzed with Rh2(OAc)4, and, in contrast to the previous reactions, the benzoyl-substituted thiirane derivative 5a was the sole product (Scheme 4). Both types of reaction were observed with α-diazo amides 1d,e (Schemes 5-7). It is worth mentioning that formation of 1,3-oxathiole or thiirane is not only dependent on the type of the carbonyl compound 2 but also on the α-diazo amide. In the case of 1d and thioxocyclobutanone 2c in THF at room temperature, the primary cycloadduct 12 was the main product. Heating the mixture to 60°, 1,3-oxathiole 10d as well as the spirocyclic thiirane-carboxamide 11b were formed. Thiirane-carboxamides 11d-g were desulfurized with (Me2N)3P in THF at 60°, yielding the corresponding acrylamide derivatives (Scheme 7). All reactions are rationalized by a mechanism via initial formation of acyl-substituted thiocarbonyl ylides which undergo either a 1,5-dipolar electrocyclization to give 1,3-oxathiole derivatives or a 1,3-dipolar electrocyclization to yield thiiranes. Only in the case of the most reactive 9H-fluorene-9-thione (2f) is the thiocarbonyl ylide trapped by a second molecule of 2f to give 1,3-dithiolane derivatives by a 1,3-dipolar cycloaddition.
    Zusätzliches Material: 3 Ill.
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  • 48
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998) 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 491-506 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of a series of chiral enantiomerically pure C2-symmetric binucleating ligands is reported. Ligands of type 1-4, which consist of a phenolic or heterocyclic unit bridging two chiral dihydrooxazole rings. are readily accessible from chiral amino alcohols. Ligands 5a and 5b are composed of a cyclic urea or thiourea unit, respectively, and two 3,4-dihydro-2H-pyrrole rings containing a stereogenic center next to the N-atom. Compounds of this type are readily assembled from ethane-1,2-diamine and an imidothioic ester derived from pyroglutamic acid. These new ligands, which can coordinate two metals in close proximity to each other, are of interest regarding possible applications in asymmetric catalysis.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 548-557 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stability constants have been measured for a series of ligands based on a 2,2′-(pyridine-2,6-diyl)bis[1H-benzimidazole] unit which forms dinuclear double-stranded helical complexes with copper(I). Variation of different structural parameters confirms the importance of the coordinate bond, the stacking interactions, and the weakly bridging pyridine units observed by X-ray crystallography. The stabilities of the complexes depend strongly on the solvent, and in MeCN, which is a good solvent for copper(I), the complexes are less stable and assemble in a stepwise manner. The interconversion of the enantiomers may be followed by 1H-NMR and takes place on a millisecond time scale around room temperature. The trends in lability are similar to those found for the stability of the complexes.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 570-583 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Oligodeoxyribonucleotides containing 7-deaza-2′-deoxy-8-methylguanosine (m8c7Gd; 2b) were prepared. For this purpose, the phosphonate 3a and the phosphoramidite 3b were synthesized and employed in solidphase oligodeoxyribonucleotide synthesis. The structures and the thermodynamic data of duplex formation of oligodeoxyribonucleotides containing 2b were investigated by temperature-dependent CD and UV spectra and compared with those containing 7-deaza-2′-deoxy-7-methylguanosine (m7c7Gd) or 7-deaza-2′-deoxy-guanosine (c7Gd; 2a). In general, compound 2b reduces the duplex stability. In case of the sequence d(m8c7G-C)4 (18), the B → Z transition was facilitated by the incorporation of 2b. Moreover, a single 7-deaza-8-methylguanine residue present in an oligodeoxyribonucleotide tract of guanine residues destabilizes the dG quadruplex significantly. This destabilization is more pronounced than in the case of 7-deazaguanine or 7-deaza-7-methyl-guanine.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 770-780 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute rate constants and their Arrhenius parameters are obtained for the addition of a cyclic malonyl radical derived from Meldrum's acid to 20 mono- or 1,1-disubstituted alkenes in (±)-propylene oxide and for the addition of the open-chain di(tert-butyl)malonyl radical to six mono- or 1,1-disubstituted alkenes in 1,1,2-trichloro-1,2,2-trifluoroethane by time-resolved electron spin resonance spectroscopy. At room temperature, the radicals add at the unsubstituted C-atoms with rate constants ranging from 1.1. 105 M-1S-1 (acrolein) to 2.4. 106 M-1S-1 (1,1-diphenylethene). The frequency factors are in the narrow ranges of log (A/M-1S-1) = 8.7 ± 0.1 for the cyclic and log (A/M-1S-1) = 8.2 ± 0.2 for the open-chain malonyl species, whereas the activation energies vary from 12.9 kJ/mol (1,1-diphenylethene) to 21.7 kJ/mol (acrylonitrile). They correlate with the alkene ionization potentials and, more weakly, with the reaction enthalpy. No correlation was found between the activation energies and the alkene electron affinities. Hence, the results confirm and quantify the electrophilic nature of malonyl radicals in addition reactions.
    Zusätzliches Material: 5 Ill.
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  • 53
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1303-1318 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An asymmetric synthesis of (-)-(4R)-dihydroisomyricoidine (28), a 13-membered amino lactam of type A, was performed by a diastereoselective Michael addition between the spermidine derivative 3 and the commercially available optically active ethyl carboxylate 4, and the cyclization of the resulting ω-amino acid 7 using diethyl phosphorocyanidate ((EtO)2POCN), followed by a Wittig reaction to introduce the (Z)-side chain. Some side reactions are also discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 54
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Natural free carboxylic acids from the hadromerid sponge Diacarnus levii (Kelly-Borges and Vacelet) were esterified to yield the new cyclic norditerpene peroxides ent-muqubilin benzyl ester (= (αR,3S,6R)-α,6-dimethyl-6-[(E)-4-methyl-6-(2,6,6-trimethyl-cyclohex-1-en-1-yl)hex-3-enyl]-1,2-dioxan-3-acetic acid benzyl ester; 6, diacarnoate B methyl ester(= (αS,3R,6R)-α,6-dimethyl-6-{2-(4aS,8aS)-3,4,4a,5,6,7,8,8a-octahydro-3-oxo-2,5,5,8a-tetramethylnaphthalen-1-yl)ethyl}-1,2-dioxan-3-acetic acid methyl ester; 9), and deoxydiacarnoate B benzyl ester (= (αS,3R,6R)-α,6-dimethyl-6-{2-[(4aS,8aS)-3,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethyl-1-naphthalenyl]ethyl}-1,2-dioxan-3-acetic acid benzyl ester; 10), which were isolated following extensive chromatography. The relative configuration of the peroxide/α-methylacetate moiety of 6, 9, and 10, was directly determined from their NMR spectra. The absolute configurations of the peroxide/α-methylacetate moiety was deduced from comparative 1H-NMR data of the (S)- and (R)-phenylglycine methyl ester derivatives 7 and 8 as well as 11/13 and 12/14, all obtained from a mixture of the precursors of 3, 6, and 10. The absolute configuration at the carbobicyclic moiety of enone 9 and of 10, is identical, as established by chemical interconversion, 9 and 10 belong to the normal labdane series according to empirical CD rules, applied either directly to 9 or to the parent (+)-sclareolide-derived enone 20. In contrast, molar rotation additivity rules suggest the ent-labdane configuration for 9 and 10. The epidioxides 1-3, 6, and 10 proved active in vitro against the malaria parasite Plasmodium falciparum; especially the previously isolated methyl 3-epinuapapuanoate (2) was active against a chloroquine-resistant strain, and this with a good security index.
    Zusätzliches Material: 1 Tab.
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  • 55
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 3-Hydroxy-2-cyanoalk-2-enamides, and 2-cyano-2-(tetrahydrofuran-2-ylidene)- and 2-cyano-2-(tetrahydropyran-2-ylidene)acetamides with N-alkyl and N-aryl substituents have been synthesized in three steps from cyanoacetic acid. Their conformations were investigated by X-ray crystallography and 1H-NMR ROESY spectroscopy at room temperature. The enolic compounds 1-3 adopt an extended conformation stabilized by a strong intramolecular O—H … O=C bond both in the solid state and in (D6)DMSO solution. In contrast, the structure of the cyclic derivatives 5a,b-8a,b is solvent-dependent. In the solid state and in CDCl3 solution, the compounds adopt an extended conformation of type I or III, while, in (D6)DMSO solution, their structures undergo time-dependent (Z)/(E)-isomerization structures (of type II or IV). This observation is compatible with a dipolar transition state of rotation. The kinetics of the isomerization are controlled by the N-substituent, the N-(t-Bu) derivatives 7a and 7b having the highest barrier of rotation around the C=C bond. The whole body of experimental evidence together with the results of molecular-mechanics calculations with I-IV, indicate that, in DMSO, two (E)/(Z)-isomers with two conformations are present, and that they undergo interconversion at room temperature with four different constants. The very fast exchange rates kI,II and kIII,IV in the NMR time-scale might be responsible for the detection of only two isomers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1393-1403 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new acylated dimeric secoiridoid glycoside, seemannoside A (2), has been isolated from the aerial parts of Lisianthius seemannii (GRISEB) O. KUNTZE (Gentianaceae). The structure was established by spectroscopic analysis (UV, MS, 1H- and 13C-NMR, and 2D-NMR experiments) and chemical reactions as (E-4′-O-p-coumaroyl)lisianthioside. The structure of the (Z)-isomer (seemannoside B, 3), also present in the plant, was confirmed by LC/UV/1H-NMR analysis. The active principle, 6, responsible for the antifungal activity of the apolar extract against Cladosporium cucumerinum, has been isolated. Its structure has been established by NMR spectroscopy and X-ray crystallographic analysis as a rare type of aglycone monoterpene dimer.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 57
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Asymmetric Diels-Alder reaction of the pentadienoic and hexadienoic acids 2a,b with the chiral chloronitroso derivative 3 gave the primary adducts 4a,b with good-to-excellent enantioselectivity. Subsequent as- or trans-dihydroxylation and hydrogenolytic cleavage of the N—O bond led to the 5-amino-5-deoxypentono-δ-lactams 13a, 14, 15a, and 16 in the D-ribose, L-arabinose, D-xylose, and L-lyxose series, respectively, and to the 5-amino-5,6-dideoxyhexono-δ-lactams 13b and 15b in the D-allose and D-glucose series, respectively.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 58
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of the monomeric building block 13 and its constitutional isomer 12 of a new type of DNA analog, distamycin-NA, is presented (Schemes 1 and 2). This building block consists of a uracil base attached to a thiophene core unit via a biaryl-like axis. Next to the biaryl-like axis on the thiophene chromophore, a carboxy and an amino substituent are located allowing for oligomerization via peptide coupling. The proof of constitution and the conformational preferences about the biaryl-like axis were established by means of X-ray analyses of the corresponding nitro derivatives 10 and 11. Thus, the uracil bases are propeller-twisted relative to the thiophene core, and bidentate H-bonds occur between two uracil bases in the crystals. The two amino-acid building blocks 12 and 13 were coupled to give the dimers 15 and 16 using dicyclohexylcarbodiimide (DCC) in THF/LiCl and DMF, respectively. While the dimer 15 showed no atropisomerism on the NMR time scale at room temperature, its isomer 16 occurred as distinct diastereoisomers due to the hindered rotation around its biaryl-like axis. Variable-temperature 1H-NMR experiments allowed to determine a rotational barrier of 19 ± 1 kcal/mol in 16. The experimental data were complemented by AM1 calculations.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 59
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heating of a mixture of N,N′-(thiocarbonyl)diimidazole (= 1,1′-(carbonothioyl)bis[1H-imidazole]; 1) and 2,5-dihydro-1,3,4-thiadiazole 2a or 2b gave the 1,3-dithiolanes 4a and 4b, respectively, via a regiospecific 1,3-dipolar cycloaddition of the corresponding ‘thiocarbonyl methanides’ 3a,b onto the C=S group of 1 (Schemes 1 and 2). The adamantane derivative 4b was not stable in the presence of 1H-imidazole and during chromatographic workup. The isolated 1,3-dithiole 5 is the product of a base-catalyzed elimination of 1H-imidazole from the initial cycloadduct 4b. The formation of the S,N-acetal 6 can be rationalized by a protonation of the ‘thiocarbonyl ylide’ 3b followed by a nucleophilic addition of 1H-imidazole. With the diazo compounds 8a-e (Scheme 3) 1 underwent a regiospecific 1,3-dipolar cycloaddition to give the corresponding 2,5-dihydro-1,3,4-thiadiazole derivatives 9, which spontaneously eliminated 1H-imidazole to yield (1H-imidazol-1-yl)-1,3,4-thiadiazoles 10. The structures of 10a and 10d were established by X-ray crystallography. In the case of diazodiphenylmethane (8f), the initial cycloadduct 9f decomposed via a ‘twofold extrusion’ of N2 and S to give 1,1′-(2,2-diphenylethenylidene)bis[1H-imidazole] (11; Scheme 3).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 60
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of new deoxyribose nucleosides by coupling chloropurines with modified D-ribose derivatives is reported. The methyl 2-deoxy-N-methyl-3-O-(p-toluoyl)-α-D-ribofuranosiduronamide (α-D-8) and the corresponding anomer β-D-8 were synthesized starting from the commercially available 2-deoxy-D-ribose (1) (Scheme 1). Reaction of α-D-8 with the silylated derivative of 2,6-dichloro-9H-purine (9) afforded regioselectively the N9-(2′-deoxyribonucleoside) 10 as anomeric mixture (Scheme 2), whereas β-D-8 did not react. Glycosylation of 9 or of 6-chloro-9H-purine (17) with 1,2-di-O-acetyl-3-deoxy-N-methyl-β-D-ribofuranuronamide (13) yielded only the protected β-D-anomers 14 and 18, respectively (Scheme 3). Subsequent deacetylation and dechlorination afforded the desired nucleosides β-D-11, β-D-12,15, and 16. The 3′-deoxy-2-chloroadenosine derivative 15 showed the highest affinity and selectivity for adenotin binding site vs. A1 and A2A adenosine receptor subtypes.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 174-181 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (S)-5,5,5,5′,5′,5′-Hexafluoroleucine ((S)-13) of 81 % ee is prepared from hexafluoroacetone (l) and ethyl bromopyruvate (= ethyl 2-oxopropanoate) in 7 steps with an overall yield of 18% (Schemes 1 and 2). Key step in this sequence is the highly enantioselective reduction of the carbonyl group in α-keto ester 4 either by bakers' yeast (91 % ee) or by ‘catecholborane’ 6 utilizing an oxazaborolidine catalyst, yielding hydroxy ester (R)-5 with 99% ee. The absolute configuration was determined by X-ray analysis of the HCl adduct (S,R)-9b of (2S)-N-[(R)- l-phenylethyl]-5,5,5,5′,5′,5′-hexafluoroleucine ethyl ester.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998) 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 63
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: N-Fmoc-Protected (Fmoc = (9H-fluoren-9-ylmethoxy)carbonyl) β-amino acids are required for an efficient synthesis of β-oligopeptides on solid support. Enantiomerically pure Fmoc-β3-amino acids β3: side chain and NH2 at C(3)(= C(β)) were prepared from Fmoc-protected (S)- and (R)-α-amino acids with aliphatic, aromatic, and functionalized side chains, using the standard or an optimized Arndt-Eistert reaction sequence. Fmoc-β2- Amino acids (β2 side chain at C(2), NH2 at C(3)(= C(β))) configuration bearing the side chain of Ala, Val, Leu, and Phe were synthesized via the Evans' chiral auxiliary methodology. The target β3-heptapeptides 5-8, a β3- pentadecapeptide 9 and a β2-heptapeptide 10 were synthesized on a manual solid-phase synthesis apparatus using conventional solid-phase peptide synthesis procedures (Scheme 3). In the case of β3-peptides, two methods were used to anchor the first β-amino acid: esterification of the ortho-chlorotrityl chloride resin with the first Fmoc-β-amino acid 2 (Method I, Scheme 2) or acylation of the 4-(benzyloxy)benzyl alcohol resin (Wang resin) with the ketene intermediates from the Wolff rearrangement of amino-acid-derived diazo ketone 1 (Method II, Scheme 2). The former technique provided better results, as exemplified by the synthesis of the heptapeptides 5 and 6 (Table 2). The intermediate from the Wolff rearrangement of diazo ketones 1 was also used for sequential peptide-bond formation on solid support (synthesis of the tetrapeptides 11 and 12). The CD spectra of the β2- and β3-peptides 5, 9, and 10 show the typical pattern previously assigned to an (M) 31 helical secondary structure (Fig.). The most intense CD absorption was observed with the pentadecapeptide 9 (strong broad negative Cotton effect at ca. 213 nm); compared to the analogous heptapeptide 5, this corresponds to a 2.5 fold increase in the molar ellipticity per residue!
    Zusätzliches Material: 1 Ill.
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  • 64
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 303-306 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On irradiation (350 nm) in the presence of excess 2,3-dimethylbut-2-ene, the newly synthesized title compound 5 affords as main products the unexpected cyclopropylpyrrolidine 10 (50%) and the spiro-oxetane 9 (25%).
    Materialart: Digitale Medien
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  • 65
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Among seventeen different Lewis acids, TiCl4 was found to be the best catalyst for the [4 + 2] cycloaddition of cyclopentadiene to N,N′-fumaroylbis[(2R)-bornane-10,2-sultam] ((-)-1). Independently of the TiCl4 molar concentration, almost constant and complete (98-89% d.e.) diastereofacial π-selection was achieved in the Diels-Alder addition of (-)-1 to cyclopentadiene, cyclohexadiene, isoprene, and 2,3-dimethylbuta-1,3-diene.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 66
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 353-373 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new facile synthesis of N,S- and N,Se-acetals starting from aldehydes and primary amines is presented (Schemes 3-5). These acetals are used as precursors for stereoselective radical deuteration and allylation reactions (Schemes 6 and 7, Tables 1 and 2). The stereochemical outcome of the reactions depends on the radical trap and the substituents at the N-atom. Deuterations give always anti products with moderate to high selectivities. The allylation reactions give either syn or anti products with low to moderate selectivities. The observed stereoselectivities can be explained with a model based on minimization of A1,3 strain and are controlled by steric and stereoelectronic effects.
    Zusätzliches Material: 1 Ill.
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  • 67
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 525-538 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Based on O-methylasparvenone (1), a N-free 5HT2C antagonist with moderate affinity (pKi = 6.7), derivatives bearing dimethylamino (7), (dimethylamino)methyl (17, 18, 21, and 22), and aminomethyl substituents (26) in place of the benzylic OH group of 1 as well as pyrrolidine- (33) and piperidine-fused derivatives (29, 43, and 45) were synthesized. In contrast to the lead structure 1, these new ligands were active in vivo in the rat. The tricycles 33 and 45 display high affinities for the 5HT2C receptor (pKi = 8).
    Zusätzliches Material: 5 Tab.
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  • 68
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermal reactions of 1,2,3-trisubstituted aziridines 1 with 1,3-thiazole-5(4H)-thiones 6 in toluene yielded, in general, a mixture of two diastereoisomeric spirocyclic [2+3] cycloadducts. The formation of these products can be explained by a stereoselective electrocyclic ring opening of 1 to give an azomethine ylide 2 as the reactive intermediate, which is trapped immediately by 6 via a stereoselective 1,3-dipolar cycloaddition. Only in the case of trans-dimethyl 1-(4-methoxyphenyl)aziridine-2,3-dicarboxylate (trans-1a), four diastereoisomeric cycloadducts were formed (Scheme 4). This result is rationalized by an isomerization of the intermediate azomethine ylide cis-2a to trans -2a.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 69
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Due to their small mass, adjacent protons (or H-atoms) of molecular systems may exhibit quantum entanglement (or quantum correlations), even at ambient conditions. The considerable thermal disturbance and/or manybody interactions of condensed matter and the associated decoherence effect, however, cause this protonic entanglement to be restricted in space and time. Some aspects of entanglement and decoherence are mentioned. Extending our previous theoretical work, in the present paper the focus is on the possible existence of entangled protons belonging to the H-bonds of adjacent base pairs of B-type DNA. Based on the ‘working hypothesis’ that this effect does really exist, the most probable ‘positions’ for the appearance of protonic entanglement in DNA sequences are qualitatively determined. Furthermore, these ‘positions’ appear to correspond uniquely to dimers of adjacent base pairs of DNA. As a consequence, one can straightforwardly search for an enhanced appearance of such entangled H-bonds in DNA sequences of living organisms, using the existing DNA databases. A quantitative analysis of protein-coding DNA sequences of various organisms has been performed, the results of which provide strong evidence for the existence of the considered effect. The most striking finding may be summarized as follows: Quantum entanglement appears preferably between the third base of a codon and the first base of the following one. Quantitative estimates of this and further obtained results are presented. It is also shown that quantum-chemical considerations of stacking energies cannot account for the results. The new findings provide first evidence for the biological significance of entangled H-bonds.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 688-694 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The title compounds D-10 and L-10 were prepared from 1 in eight steps and in a combined overall yield of 41-49%.
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  • 71
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of N,N'-dimethyl-2-nitroethene-1,1-diamine (8) with α,ß-unsaturated acyl isothiocyanates 9 affords 3,3-diamino-2-nitroacrylthioamides 10 (Scheme 2) in moderate-to-good yields. Cyclization of 10 under acidic conditions gives 1,3-thiazin-4-one derivatives of type 11. Oxidative cyclization of 10 with diethyl azodicaboxylate leads to 4-nitro-1,2-thiazol-5(2H)-imine derivatives 12.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 754-763 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The CH2Cl2 extract of Monotes engleri Gilg. (Dipterocarpaceae) showed antifungal activity against the yeast Candida albicans in our bioautographic TLC assays. After a first fractionation of the crude extract, the bioactivity was located in one of the fractions. To perform an efficient targeted isolation of the active compounds, LC/UV/MS and LC/UV/NMR analyses of the crude extract and the active fraction were performed. LC/UV/, LC/MS, and LC/NMR data (1D and 2D) allowed the identification of 1 as (2S)-2,3-dihydro-5,7-dihydroxy-{3-hydroxy-4-[(3-methylbut-2-enyl) oxy]phenyl}-4H-1-benzopyran-4-one, a new prenylated flavanone, named monoteson A. Subsequent isolation of 1 has permitted the determination of its absolute configuration on the basis of CD measurements. Theree other prenylated flavanoes 2-4 were isolated from the same extract. Compound 3 was identified as 2- (3, 5-dihydroxyphenyl) -2,3-dihydro-5, 7-dihydroxy-6, 8-bis (3-methylbut-2-enyl)-4 H-1-benzopyran-4-one, another new natural product, named monotesone B. The structures of 2 and 4 were established as selinone and lonchocarpol A, respectively. The antifungal activity against Candida albicans was determined for all compounds.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 73
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The disubstituted clusters[Ir4(CO)10(μ2-L—L)] with one edge-bridging ligand have a ground-state geometry with all COs terminal (L—L = (MeS)2CHMe, cluster 1) or with three edge-bridging COs (L—L = (Ph2P)2CHMe, cluste 2; L—L =Ph2P(CH2)3PPh2, cluster 3) in the solid state and in solution. A comparative 13C-NMR study of 1-3 shows that their respective ground-state geometries are merely relative minima of energy in the same kinetic profile of successive fluxional processes consisting of a merry-go-round of six COs about a unique trangular face and the rotation of terminal COs about one Ir-atom. The factors affecting the activation energy of the merry-go-round result from the relative bites of the bidentate ligands in the ground-state geometry, as shown by a comparison of the molecular structures of 2 and 3.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 74
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the reaction between pyridoxal 5′-phosphate (PLP) with carbidopa, hydralazine, and isoniazid, in aqueous solution at variable pH and constant ionic strength of 0.1M was studied spectrophotometrically. The rate constants of formation and hydrolysis of the resulting Schiff base, and its stability were determined in a wide range of pH. A comparison is made of the formation rate constants with those of PLP with hydrazine. The reactivity shows the sequence isoniazid 〉 hydrazine 〉 carbidopa 〉 hydralazine in the whole range of pH studied. The Schiff bases studied are more stable than those formed by PLP and hexylamine and as stable as those described for the reactions of PLP with poly(L-lysine) or copolypeptides containing L-lysine.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 507-524 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The coordination behavior of chiral binucleating ligands of type 1-4 with various transition metals has been investigated. 1H-NMR Titration experiments with zinc(II) salts gave detailed structural information about the structure of the resulting zinc complexes. Ligand 1 forms an unusual C3-symmetric dinuclear zinc complex [Zn2CIL3] (8a) which was characterized by X-ray crystallography. Treatment of complex 8a with various carboxylic acids resulted in ligand-exchange reactions. With ligand 2, a hydroxo-bridged dinuclear copper complex 15 was synthesized and its structure elucidated by X-ray analysis. Solution studies UV and 1H-NMR spectroscopy of the reaction of ligand 3 with ZnII and NII salts revealed the formation of dimeric species of the type [M2X4L2]. Ligand 4 formed well-defined dinuclear complexes with NiII and CuII salts of which the corresponding NiII complex [Ni2(AcO)2(ClO4)2L] (22a) was characterized by crystal-structure analysis.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 76
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Why Pentose- and Not Hexose-Nucleic Acids? Purine-Purine Pairing in homo-DNA: Guanine,Isoguanine, 2,6-Diaminopurine, and XanthineThis paper concludes the series of reports in this journal [1-4] on the chemistry of homo-DNA, the constitutionally simplifie dmodel system of hexopyranosyl-(6′ → 4′)-oligonucleotide systems stidued in our laboratory as potentially natural-nucleic-acid alternatives in the context of a chemical aetiology of nucleic-acid structure. The report describes the synthesis and pairing properties of homo-DNA oligonucleotides which contain as nucleobases exclusively purines, and gives, together with part III of the series [3], a survey of what we know today about purine-purine pairingin homo-DNA. In addition, the paper discusses those aspects of the chemistry of homo-DNA which, we think, influence the way how some of the structural features of DNA (and RNA) are to be interpreted on a qualitative level.Purine-purine pairing occurs in the homo-DNA domain in great variety. Most prominent is a novel tridentate Watson-Crick pair between guanine and isoguanine, as well as one between 2,6-diaminopurine and xanthinone, both giving rise to very stable duplexes containing the all-purine strands in antiparallel orientation. For the guanine-isoguanine pair, constitutional assignment is based on temperature-dependent UV and CD spectroscopy of various guanine- and isoguanine-containg duplexes in comparison with duplexes known to be paired in the reverse guanine is replaced by 7-carbauguanine. Isoguanine and 2,6-diaminopurine also have the capability of self-pariring in the reverse-Hoogsteen mode, as previously observed for adenine and guanine [3]. In this type of pairing, the interchangeably. Fig. 36 provides an overall survey of the relative strength of pairing in all possible purine-purine combinations.Watson-Crick pairing of isoguanine with guanine demands the former to participate in its 3H-tautomeric form; hitherto this specific tautomer had not been considered in the pairing chemistry of isoguanine. Whereas (cumulative) purine-purine pairing in DNA (reverse-Hoogsten or Hoogsteen) seems to occur in triplexes and tetrapalexes only, its occurrence in duplexes in a characteristic feature of homo-DNA chemistry. The occurrence of purine-purine Watson-Crick base pairs is probably a consequence of homo-DNA's quasi-linear ladder structure [1][4]. In a double helix, the distance between the two sugar C-atoms, on which a base pair is anchored, is expected to be constrained by the dimensions of the helix; in a linear duplex, however, there would be no restrictions with regard to base-pair length. Homo-DNA's ladder-like model also allows one to recognize one of the reasons why nucleic-acid duplexes prefer to pair in antiparallel, rather than parallel strand orientation: in homo-DNA duplexes, (averaged) backbone and base pair axes are strongly inclined toward one another [4]; the stronger this inclination, the higher the preference for antiparallel strand orientation is expected to be (Fig. 16).In retrospect, homo-DNA turns out to be one of the first artificial oligonucleotide systems (cf. Footnote 65) to demonstrate in a comprehensive way that informational base pairing involving purines and pyrimidines is not a capability unique to ribofuranosyl systems. Stability and helical shape of pairing complexes are not necessary conditions of one another; it is the potential for extensive conformational cooperativity of hte backbone structure with respect to the constellational demands of base pairing and base stacking that determines whether or nor a given type of base-carrying backbone structure is an informational pairing system. From the viewpoint of the chemical aetiology of nucleic-acid structure, which inspired our investigations on hexopyranosyl-(6′ → 4′)-oligonucleotide systems in the first place, the work on homo-DNA is only an extensive model study, because homo-DNA is not to be considered a potential natural-nucleic-acid altenratie. In retrospect, it seems fortunate that the model study was carried out, because without it we could hardly have comprehended the pairing behavior of the proper nucleic-acid alternatives which we have studied later and which will be discussed in Part VI of this series.The English footnotes to Fig. 1-49 provide an extension of this summary.
    Zusätzliches Material: 49 Ill.
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  • 77
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ‘Fully chiral’ dendrimers, containing a stereogenic center at each and every branching point, have been prepared using a chiral core triol with aromatic elongating units (cf. 27) and chiral branch diols (cf. 8, 12, and 24) as building blocks. The biggest dendrimer prepared is of the 4th generation (33: 46 building blocks, 93 stereogenic centers, 1028 possible stereoisomers), and has been obtained by a convergent growth approach in 32 steps starting from the biopolymer poly[(R)-3-hydroxybutanoic acid] (P(3-HB)). All compounds were shown to be monodisperse by MALDI-TOF mass spectrometry. Spin-lattice relaxation-time (T1) measurements and size-exclusion chromatography show typical features of structurally related achiral dendrimers. The influence of the chiral building blocks on the shape of the whole dendrimer has been investigated by chiroptical measurements: the specific rotation can be considered as average of all chiroptical properties of its constituent chiral units, independent of the solvent, the concentration, and the temperature. On the other hand, regularity in the circular dichroism (CD) spectra is completely lost with variation of the solvent (cf. Fig. 13).
    Zusätzliches Material: 11 Ill.
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  • 78
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998) 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 79
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The first steps, believed to be involved in the highly enantioselective copolymerization of styrene and carbon monoxide to poly[1-oxo-2-phenylpropane-1,3-diyl] with phosphinodihydrooxazole-palladium(II) complexes, were investigated. The insertion of carbon monoxide into [Pd(Me)(P^N)(solvent)] TfO (P^N = (S)-2-[2-(5H-benzo[b]phosphindol-5-yl)phenyl]4-benzyl-4,5-dihydrooxazole (1)) and of styrene into [Pd(Me)(P^N)(solvent)] TfO were highly regioselective (alkyl and acyl substituents trans to N); moreover, the olefin insertion took place with essentially complete enantioface discrimination.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998) 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 81
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The [4 + 2] cycloadduct 17 of 2,3-dimethylidene-1,2,3,4-tetrahydro-1,4-methanonaphthalene and 4-phenyl-4H-1,2,4-triazole-3,5-dione (PTAD) was subjected to a triplet-sensitized di-π-methane rearrangement. Hydrolysis of the resulting urazol 18 gave the hydrocarbon 7. Hydrolysis of 18 at lower base concentrations led to isomeric stable semicarbazides 24 and 25, which were submitted NiO2 or MnO2 oxidation, to give the target compound 7, and oxidation products 26 and 27.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 82
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The difference between the strong inhibition of retaining β-glucosidases by the tetrazole 1 and the weak inhibition by the triazole 3 has been explained by the protonation by the enzymic catalytic acid of N(3) of 1, replaced by CH in 3. One also expects a contribution to the inhibition from the charge-dipole interaction between the enzymic catalytic nucleophile and the azole ring. The extent of this contribution was estimated from the calculated, distance-dependent heats of formation of the acetate-azole complexes. The calculations were validated by comparison of the charge-dipole interaction between phosphate and the inhibitors 1 and 3 in the glycogen phosphorylase b (GPb)-azole-phosphate complexes, as derived from differences in the Ki values for 1 and 3, while the structural invariance of the complexes was demonstrated by X-ray analysis. The difference between the charge-dipole interactions of (dihydrogen) phosphate and 1 or 3 as derived from Δ Ki is 1.1 kcal mol-1, while the calculated difference is 1.3 kcal mol-1. The calculated difference for the interaction of 1 or 3 with acetate, representing the catalytic nucleophile in β-glycosidases, is 2.0 kcal mol-1, while the differences of the binding energies as derived from the Ki values for the inhibition by 1 or 3 of different β-glycosidases range from 2.4 to 5.3 5 kcal mol-1. The calculated difference for 1 and the imidazole 6 is 2.5 kcal mol-1 in favour of 1, whereas the Ki-derived difference is 3.7 kcal mol-1 in favour of 6, equal to the calculated difference between 1 and the protonated imidazole 6. Thus, protonation by the catalytic acid and the charge-dipole interaction with the catalytic nucleophile contribute cooperatively to the binding of inhibitors possessing a trigonal anomeric centre bonded to a heteroatom.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 902-915 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Described are the preparation of nanocrystals and the synthesis of molecules that may be covalently or noncovalently assembled in solution to yield heterosupermolecules possessing a well-defined heterosupramolecular function. Also described are preparative and synthetic methods that yield organized assemblies of heterosupermolecules possessing an addressable heterosupramolecular function. Finally, the development of these synthetic strategies to permit the covalent and noncovalent assembly and organization of a wide range of condensed phase and molecular components is outlined.
    Zusätzliches Material: 1 Tab.
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  • 84
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For a comparison with the corresponding α- and β-hexapeptides H-(Val-Ala-Leu)2-OH (A) and H-(β-HVal-β-HAla-β-HLeu)2-OH (B), we have now prepared the corresponding γ-hexapeptide 1 built from the homochirally similar (S)-4-aminobutanoic acid, (R)-4-amino-5-methylhexanoic acid, and (R)-4-amino-6-methylheptanoic acid. The precursors were prepared either by double Arndt-Eistert homologation of the protected amino acids Boc-Val-OH, Boc-Ala-OH, and Boc-Leu-OH (Schemes 1 and 2), or by the superior route involving olefination/hydrogenation of the corresponding aldehydes (Boc-valinal, Boc-alaninal, and Boc-leucinal; Scheme 3). Conventional peptide-coupling methodology (EDC/HOBt) furnished the γ-hexapeptide 1 (through the intermediate γ-di- and γ-tripeptide derivatives 9-11). Analysis of NMR measurements in (D5)pyridine and CD3OH solution (COSY, TOCSY, HSQC, HMBC, ROESY) reveals that the γ-hexapeptide 1 adopts a right-handed helical structure ((P)-2.61 helix of ca. 5-Å pitch, containing 14-membered H-bonded rings) which is to be compared with the left-handed helix of the corresponding β-peptide B ((M)-31 helix of 5-Å pitch, 14-membered H-bonded rings) and with the familiar right-handed, so-called α-helix of α-peptides ((P)-3.61 helix of 5.4-Å pitch, 13-membered rings). Like the helix sense, the helix dipole reverses when going from α-, (N + → C) to β-(C + → N) to γ-peptides (N + → C). The surprising difference between the natural α-, and the analogous β- and γ-peptides is that the helix stability increases upon homologation of the residues.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 85
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 7-O-Substituted analogs of deaminodeoxycolchinol thiomethyl ether were synthesized and evaluated for their inhibitory effects on tubulin polymerization in vitro. Ketone 9, a key compound in this study, was derived from thiocolchicone 6 by reaction with aniline. Reaction of compound 6 with MeNH2 or BuNH2 gave tetracyclic lactams 7 and 8, respectively. Optically active alcohols 11a and 11b were obtained from racemic 11 by chemical resolution including a separation of the comphanate diastereoisomers 12a and 12b, followed by basic hydrolysis. The (aR,7R)-configuration of 12b was verified by X-ray crystallographic analysis. Almost all racemic and optically active 7-O-acyl or 7-O-aroyl compounds had strong inhibitory effects on the tubulin polymerization reaction, with IC50 values from 1.7 to 5.1 μM. A few agents, such as the lactams 7 and 8, the camphanates 12a and 12b, the cyclohexanecarboxylates 19a and 19b, and, most notably, the (7S)-benzoate 15a, had negligible effects on polymerization, yielding IC50 values greater than 40μM. Ketone 9 showed strong inhibition of tubulin polymerization comparable to that of thiocolchicone (6). Optically active alcohol 11a and acyl esters 13a and 14a with a (7S)-configuration were more active than the (7R)-esters 13b and 14b. However, the esters 15a-17a with a (7S)-configuration were less active than the (7R)-isomers 15b-17b, in which the (7R)-benzoate 15b was at least 15-fold more inhibitory than the (7S)-isomer 15a. For the most part, the agents causing strongest inhibition of polymerization also caused the greatest inhibition of [3H]colchicine binding. NMR and optical rotatory data indicate that, in polar solvents, the equilibrium in esters with a 7-O-aroyl substituent, i.e., 15a,b, 16a,b, and 17a,b, is reversed from (aS) to (aR) or from (aR) to (aS), as compared to nonpolar solvents.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 86
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: As a continuation of our previous studies on the synthesis and antiplatelet activity of quinolin-2(1H)-ones with an α-methylidene-γ-butyrolactone substituted at O(8), the O(6)- and N(1)-substituted isomers were synthesized and evaluated for antiplatelet activity against thrombin (Thr)-, arachidonic acid (AA)-, collagen (Col)-, and platelet-activating-factor (PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 6-hydroxyquinolin-2(1H)-one via alkylation and Reformatsky-type condensation (Schemes 1 and 2). All of them were found to inhibit the platelet aggregation perfectly which was induced by AA and Col. 6-Substituted isomers 5b-g exhibited very strong inhibitory activities against AA- and PAF- induced aggregation and are approximately ten times more potent than their 8-substituted counterparts. However, the 1-substituted (11a and 11b) and the 1,6-disubstituted (6) counterparts were relatively inactive. Their effects on the Ca2+-dependent vasoconstriction induced by high K+, and the phasic and tonic vasoconstrictions induced by norepinephrine (NE) in rat aorta were also evaluated. Except 5g, all of them were found to have significant inhibitory activity on the NE-induced phasic and tonic vasoconstrictions. Compounds 6 and 11b also exhibited strong inhibitory activity on high-K+ medium, Ca2+-induced vasoconstriction.
    Zusätzliches Material: 1 Ill.
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  • 87
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1095-1104 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolysis of N-alkylpyridinium halides 9a-e in alkaline H2O gave 6-azabicyclo[3.1.0]hexenol derivatives 10a-e. N-Substituents bearing ether, acetal, and alcohol functions were found to do not adversely influence the photochemical reaction course. The free OH groups of the N-(3-hydroxypropyl) derivative 10d were protected by benzoylation. The ensuing dibenzoate 14 underwent stereocontrolled opening of the aziridine ring on reaction with MeSH/BF3 to give a thioether 15. With benzoic acid in CHCI3, 10d gave the 4-hydroxy-5-aminocyclopent-2-enyl benzoate 11. The meso-2-aminocyclopent-4-ene-1,3-diol 12 was obtained by hydrolysis of 11. On reaction with Boc2O and NaI, the aziridine ring of 14 was converted to a bicyclic compound 17. Hydrolysis of 17 provided the trans-1,3-diol 18, the epimer of 12. Face-selective dihydroxylation of Boc-protected 12 gave a meso-aminocyclopentanetetrol 23 which was characterized upon peracetylation. Dihydroxylation of 15 provided a racemic analogue of epi-mannostatin A (26).
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  • 88
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 729-733 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An alternative synthesis of enantiomerically pure SDZ 220-881 (1a) and SDZ EAB 515 (1b) starting from L-Z-tyrosine is described.
    Materialart: Digitale Medien
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  • 89
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bicyclic thiohydantoins were synthesized in a stereoselective manner by reacting (2R)/(2S)-diastereoisomer mixtures of 1,3-thiazolidine-2,4-dicarboxylic acids or their dimethyl diesters with PhNCS. 5,5-Dimethyl-1,3-thiazolidine-2,4-dicarboxylic acid with PhNCS led to a cyclization involving the C=O group at the C(2) center of the thiazolidine ring, while the acid's dimethyl diester gave cyclization involving the C=O group at C(4). In contrast, reactions involving unsubstituted 1,3-thiazolidine-2,4-dicarboxylic acid or its dimethyl diester led to thiohydantoins in which the ring closure had taken place only with the COO group at C(4). Independently of the direction of the ring closure, all reactions produce exclusively products with the (R)-configuration at C(2). The configurational assignments were based on 1H- and 13C-NMR studies, and confirmed by X-ray crystallographic analyses.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 676-687 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new, axially chiral bis(4,5-dihydrooxazoles) 4 have been synthesized in a straightforward manner, starting from the substituted, racemic 1,1′-biphenyl-2,2′-dicarboxylic acids 1 and optically active amino alcohols 2. The adducts were resolved by medium-performance liquid chromatography (MPLC; see Scheme 1). Formation of Cu1 complexes of 4 was followed by 1H-NMR spectroscopy. The catalytic behavior of these complexes has been investigated by asymmetric cyclopropanation of styrene with ethyl diazoacetate. Beside the influence of steric factors, a significant electronic effect on asymmetric induction could also be observed (see Scheme 2 and Table).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 91
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of the enantiomerically pure, bridgehead-functionalized bicyclo[3.2.1]octanes 11 and 16, containing a conformationally fixed trihydroxypropyl (aminodihydroxypropyl) unit, as well as the X-ray structure of 11 are described. These compounds are of interest as sugar surrogates in the preparation of DNA analogs. Compounds 11 and 16 became available in 10 and 12 steps, respectively, and in an overall yield of 11 and 4% from D-arabinose via a highly stereoselective pinacol coupling as the key step.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 92
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1349-1358 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New derivatives of campholenaldehyde (= 2-(2,2,3-trimethylcyclopent-3-enyl)ethanal bearing two cyclopropane moieties were synthesized, and the structure of the stereoisomer responsible for its exceptionally strong, diffusive, and natural sandalwood-oil scent, ((1S,2S)-1-methyl-2-{[1S,3R,5R)-1,2,2-trimethylbicyclo[3.1.0]hex-3-yl]methyl}cyclopropyl)methanol (13a), was elucidated.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 93
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Titanium-dioxide surfaces have been glycosylated with the benzyl-, 4-fluorobenzyl-, and acetyl-protected diazirines 1-3. The modified TiO2 surfaces were characterized by contact-angle measurement, X-ray photoelectron spectroscopy (XPES), and time-of-flight secondary-ion mass spectrometry (ToF-SIMS). The main by-products of the glucosidation (mostly azines and trehaloses) were identified. Their physisorption slightly reduces the efficiency of the glucosidation by 1 mM solution of 1 or 2 in CH2Cl2, but this influence is neutralized by repeating the glucosidation, or by using a 100 mM solution of the diazirines. The immobilized, acetylated glucosyl moieties were deacetylated in situ. Calculations based on the XPES peaks of Ti 2p and F 1s for the TiO2 surface modified with 2 indicated 1.5 ± 0.9 immobilized glucosyl moieties per nm2.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 94
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A Chemotaxonomic survey for biologically active compounds from Malaysian Calophyllum species led to the findings of the four new benzoylcoumarins 1a, 2, 3, and 4a (including the unusual prenylated 6-benzoylcoumann 1a), two uncommon coumarins 5 and 6a with a pyran-4-one moiety fused at C(6) and C(7), and compounds 7a, 9, and 10, all isolated from the bark of C. teysmannii var. inophylloide. Their structures were determined by spectroscopic analysis and chemical transformations. X-Ray crystal-structure determination of 2 provided information on the conformational preferences of substituents in this class of coumarins. The syntheses of the cytotoxic calanone (7a) and of some related coumarins are described.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 95
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1506-1520 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The heme-thiolate protein chloroperoxidase (CPO) catalyzes the chlorination of activated C—H bonds. A reaction mechanism is proposed for this enzymatic transformation (Scheme 1), and a new iron(III) porphyrinate complex 13 is synthesized containing pentafluorophenyl groups at two meso-positions and a thiophenolato ligand coordinating to the Fe-atom (Schemes 2 and 3). Due to the presence of the electron-withdrawing substituents, the catalyst 13 is appreciably resistant to oxidants (HOCl) and chlorinates, e.g., monochlorodimedone (5), with turnover numbers up to 1530. The redox potential of 13, E0 = - 134 mV, and the Soret band (λmax 448 nm) of the CO adduct of the reduced state of 13 are close to the corresponding values of the enzyme CPO.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 96
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The chemical synthesis of 2′-amino-2′-deoxyribonucleosides of uracil, cytosine, adenine, and guanine, and their conversion into suitably protected 3′-phosphoramidite building blocks 35-40 for oligonucleotide synthesis are described. The aglycone and the 2′-amino functions were protected using the 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) group. The synthesis of the 3′-O-succinyl (3′-O-(3-carboxypropanoyl))-substituted starting nucleoside 41 is described and its behavior examined in solution and on solid phase with regard to an anticipated migration during 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) deprotection. Oligonucleotides were prepared using the new building blocks, and their hybridization properties were studied by UV-melting techniques.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 97
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1583-1583 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 98
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1-13 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Chiral supermolecules may be obtained from suitable achiral molecular constituents associated through a dissymmetrizing interaction mode. This is the case for the supermolecules I-IV formed by hydrogen-bonding association between the achiral complementary components 1a,b and 2a,b,c. The crystal structures of the supermolecular pairs I-III and of the homochiral aggregate of two ternary supermolecules IV have been determined. The structural data are discussed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 46-58 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various bifunctional amino-protecting groups such as the phthaloyl, succinyl, and glutaryl group were investigated as potential linker molecules for attachment to solid-support materials. Pentane-1,3,5-tricarboxylic acid 1,3-anhydride (16) offered the best properties and reacted with the amino groups of differently sugar-protected adenosine (see 20 and 22), cytidine (see 29), and guanosine derivatives (see 32) to the corresponding 2-(2-carboxyethyl)glutaryl derivatives 23, 24, 30, and 33. The usefulness of the new linker-type molecules was demonstrated by the solid-support synthesis of the potentially antivirally active 3′-deoxyadenylyl-(2′-5′)-2′-adenylic acid 2′-{2-[(adenin-9-yl)methoxy]ethyl} ester (38) starting from the 2′-end with N6,N6-[2-(2-carboxyethyl)glutaryl]-9-{{2-[(4,4′-dimethoxytrityl)ethoxy]methyl}adenine (12).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 85-92 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An efficient stereocontrolled synthesis of (S)-N-Cbz-serine (Cbz = benzyloxycarbonyl; 12) and of its (R)-enantiomer is reported. Kinetic resolution of the easily available racemic 3-(hydroxymethyl)-1,4-benzodiazepin-2-ones is performed in the key step via acetylation by the immobilized Mucor miehei lipase (Lipozyme IM) at 60°. This method is characterized by high enantiomer purity (ee's ges; 99%) of the intermediary alcohols (+)-8 and (+)-9 and acetates (-)-10 and (-)-11, as well as of the final products (S)- and (R)-N-Cbz-serine, simple recycling of the biocatalyst, complete recovery of 2-aminobenzophenones (3 and 4) and their recycling into production of 1,4-benzodiazepines, and possibility to selectively racemize ‘wrong’ enantiomers of the alcohols 8 and 9 in the presence of Amberlite CG 400.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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