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  • Articles: DFG German National Licenses  (718)
  • 1985-1989  (718)
  • 1915-1919
  • 1987  (718)
  • Organic Chemistry  (684)
  • Magnetic resonance imaging
  • Nuclear reactions
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  • Articles: DFG German National Licenses  (718)
Material
Years
  • 1985-1989  (718)
  • 1915-1919
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Anatomic correlation of cadaver cryomicrotomy with magnetic resonance imaging (1987)
    Springer
    Surgical and radiologic anatomy 9 (1987), S. 299-302 
    Details
    ISSN: 1279-8517
    Keywords: Cryomicrotomy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La réalisation de coupes congelées dont l'épaisseur varie entre 5 et 50 μm, sur prélèvements cadavériques humains frais et non décalcifiés a été mise au point en Suède par l'un des auteurs en 1983. Cette technique permet d'obtenir des images anatomiques de haute définition qui ont été corrélées avec des coupes en IRM réalisées à des intervalles de 20 μm.
    Notes: Summary The performance of frozen sections of a thickness varying between 5 and 50 μm in fresh undecalcified cadaveric human specimens was perfected in Sweden by one of the authors in 1983. This technique makes it possible to obtain anatomic images of high definition which were correlated with MRI sections made at intervals of 20 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02105301
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of the heart compared with anatomic and ultrasonographic data (1987)
    Springer
    Surgical and radiologic anatomy 9 (1987), S. 303-314 
    Details
    ISSN: 1279-8517
    Keywords: Magnetic resonance imaging ; Ultrasonography ; Heart
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs présentent un travail de corrélation entre l'aspect anatomique du cœur et les images obtenues en imagerie par résonance magnétique (IRM) et en échographie. Six cœurs ont été étudiés par IRM puis découpés suivant les mêmes plans de coupe. Les résultats sont présentés et comparés aux données obtenues in vivo chez des volontaires à la fois en IRM et en échographie. La corrélation entre images IRM de pièces anatomiques et coupes anatomiques est excellente, les plus fins détails anatomiques étant reproduits. L'utilisation de coupes en double obliquité permet l'obtention d'incidences similaires à celle de l'échographie. Ces mêmes incidences peuvent être obtenues in vivo. L'étude morphologique du cœur est ainsi extrêmement précise, de même que l'étude des volumes cardiaques.
    Notes: Summary The authors present a correlation study between the anatomy of the heart and its appearance with magnetic resonance imaging (MRI) and ultrasonography (US). Six hearts were studied by MR, then sliced along the same planes. The results are presented and compared with the data obtained in volunteers by MRI and ultrasonography. The correlation between the MRI of isolated hearts and their anatomic slices is excellent, the thiniest anatomic details are reproduced. The use of double oblique slices provides incidences similar to those of ultrasonography. The same incidences can be obtained in vivo. The morphologic study of the heart by these imaging techniques is thus very precise, as well as the study of cardiac volumes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02105302
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging for evaluating neurogenic dysphagia (1987)
    Springer
    Dysphagia 2 (1987), S. 40-45 
    Details
    ISSN: 1432-0460
    Keywords: Neurogenic dysphagia ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dysphagia due to CNS pathology usually stems from one of two patterns of disease: (1) bilateral corticobulbar tract dysfunction (“pseudobulbar palsy”) or (2) pontomedullary dysfunction (“bulbar palsy”). Computed tomography (CT) has proved to be useful for evaluating the brainstem in patients with neurogenic dysphagia. Nonetheless, artifacts are common in CT imaging of the posterior fossa. Also, direct sagittal imaging is not usually obtainable by CT in adult patients. Magnetic resonance imaging (MRI), in contrast to CT, simultaneously gathers sequential images in the same plane and can obtain direct reconstructions in any plane of interest. MRI has proven to be more sensitive than CT in demonstrating lesions of the brain, such as demyelinating (e.g., multiple sclerosis) and ischemic diseases, (Brant-Zawadzki et al. 1984, Bradley et al. 1984, Bydder et al. 1982, Sheldon et al. 1985) as well as neoplastic masses that may produce neurogenic dysphagia (Lee et al. 1985, Zimmerman et al. 1986). Five patients with dysphagia are reported for whom MRI was valuable in detecting and characterizing their lesions of the brainstem and the cerebral hemispheres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02406977
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of the liver by frontal (coronal) sections (1987)
    Springer
    Surgical and radiologic anatomy 9 (1987), S. 107-121 
    Details
    ISSN: 1279-8517
    Keywords: Magnetic resonance imaging ; Liver ; Topographic anatomy ; Frontal (coronal) sections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Habituellement, les coupes frontales du foie en résonance magnétique sont moins utilisées que les coupes passant par les autres plans de l'espace. Des coupes frontales du tronc en résonance magnétique intéressant le foie, réalisées chez plus de 80 patients pour des indications diverses, ont été confrontées avec des coupes frontales du tronc faites sur 10 cadavres. Un schéma général de l'anatomie du foie étudiée dans le plan frontal a été établi. Les coupes frontales en résonance magnétique permettent de faire une très bonne estimation de la morphologie et du volume du foie, et d'en reconnaître les variations individuelles. Elles montrent bien certains rapports inférieurs du foie. Surtout, les coupes frontales en résonance magnétique permettent d'identifier la plupart des principales veines du foie, veines sus-hépatiques et branches de la veine porte et de bien étudier toute la portion rétro-hépatique de la veine cave inférieure. Certaines images vasculaires sont retrouvées presque constamment d'un sujet à l'autre sur les coupes. Le foie droit se prête mieux à cette étude que le foie gauche, en raison de sa morphologie et de la disposition de ses veines. Les coupes frontales du foie en résonance magnétique représentent un moyen privilégié pour étudier l'anatomie du foie. Associées à des coupes transversales, elles permettent de préciser le siège et les rapports veineux à l'intérieur du foie d'un processus pathologique, en vue d'une hépatectomie.
    Notes: Summary In general, frontal sections of the liver in magnetic resonance imaging are used less than sections passing through other planes of space. Frontal sections of the trunk in magnetic resonance imaging involving the liver, performed in over 80 patients for various reasons, were compared with frontal sections of the trunk made in 10 cadavers. A general schema was established of the anatomy of the liver studied in the frontal plane. Frontal sections in magnetic resonance imaging make it possible to form a very good estimate of the structure and size of the liver, and to recognize individual variations. They clearly show certain inferior relations of the liver. In particular, frontal sections in magnetic resonance imaging make it possible to identify most of the main veins of the liver, the main lobar veins and branches of the portal vein, and to properly study the entire retrohepatic portion of the inferior vena cava. Some of the vascular images were found almost constantly in the sections of the various subjects. The right lobe of the liver is more accessible to such study than the left by reason of its structure and its venous arrangements. Frontal sections of the liver in magnetic resonance imaging constitute a preferential method for studying the anatomy of the liver. Together with transverse sections, they make it possible to specify the site and venous relations of a pathologic process within the liver, with a view to hepatectomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02086596
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  • 5
    Electronic Resource
    Electronic Resource
    Anatomy of the thoracic aorta: Magnetic resonance imaging and interpretation of flow phenomena (1987)
    Springer
    Surgical and radiologic anatomy 9 (1987), S. 141-149 
    Details
    ISSN: 1279-8517
    Keywords: Magnetic resonance imaging ; Thoracic aorta ; Gated acquisition ; Oblique slices ; Flow Phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs présentent les résultats d'une investigation concernant l'imagerie par résonance magnétique de l'aorte thoracique d'après l'étude de huit volontaires et d'un patient suspect de maladie de Takayasu mais ayant une aorte morphologiquement normale. Des coupes axiales, frontales, sagittales et obliques ont été réalisées et les résultats morphologiques sont présentés. De plus, les principaux phénomènes de flux sont expliqués et des exemples de chacun sont montrés.
    Notes: Summary The authors present the results of magnetic resonance imaging (MRI) in the investigation of the anatomy of the thoracic aorta in a group of eight volunteers and in one patient with presumptive Takayasu's disease but with normal aorta. Transaxial, coronal, sagittal and oblique slices were made and the morphologic results are presented. Major flow phenomena are also discussed and some examples given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02086599
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of colloid cysts of the third ventricle (1987)
    Springer
    Neuroradiology 29 (1987), S. 10-14 
    Details
    ISSN: 1432-1920
    Keywords: Colloid cyst of the third ventricle ; Third ventricle ; Brain tumor ; Computer tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cases of colloid cyst of the third ventricle are reported. Their computed tomographic (CT), magnetic resonance (MR) and neuropathological features are presented. The MR findings were different in the two cases for reasons not yet fully explained, full biochemical and biophysical analyses of the cyst contents not being available. Neuropathologically, the only significant difference was the abundant presence of cholesterin crystals in the colloid of case 1 and their absence in case 2. One of our cases is also peculiar from a CT point of view, since it was primarily hypodense and did not enhance on intravenous contrast administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341029
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  • 7
    Electronic Resource
    Electronic Resource
    Advantage of magnetic resonance imaging in the diagnosis of cerebral infections (1987)
    Springer
    Neuroradiology 29 (1987), S. 120-126 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Cerebral infections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 18 patients with cerebral infections were investigated with a 1.5 Tesla-Magnetom. The results are compared to CT-findings obtained at the same time. In the majority of cases (n=11) MR is superior to CT because it allows earlier detection of the disease, a more exact definition of the spread and a more detailed representation of complex inflammatory processes. MRI should rank first among all examination methods, especially in the determination of herpes simplex-encephalitis as it allows earlier detection and treatment of this disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327535
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  • 8
    Electronic Resource
    Electronic Resource
    MR brain scanning in patients with vasculitis: differentiation from multiple sclerosis (1987)
    Springer
    Neuroradiology 29 (1987), S. 226-231 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Systemic lupus erythematosus ; Behcet's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We performed MR (magnetic resonance) brain imaging on 24 patients with a systemic vasculitis. MRI proved to be a sensitive method for detecting brain lesions (clinically silent or manifest) in these patients. The most frequent abnormalities were periventricular lesions seen in 12 cases. Such changes are not specific for vascular disease, and are often seen in multiple sclerosis. However, additional changes were commonly seen which suggested the correct diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451758
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of human cerebral infarction: Enhancement with Gd-DTPA (1987)
    Springer
    Neuroradiology 29 (1987), S. 422-429 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Gadolinium-DTPA (Gd-DTPA) ; Brain infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five patients (1 female and 4 males) with cerebral infarction of 4 h to 27 months duration were studied 9 times with magnetic resonance (MR) using Gd-DTPA. Spin-echo (SE) MR images (MRI) were obtained before and after the administration of Gd-DTPA, and correlative CT scans were performed on the same day. In 2 cases, 4 h and 27 months after the ictus, there was no enhancement with Gd-DTPA. There was faint enhancement in 2 cases with cerebral infarction of about 24h duration and obvious enhancement in all cases in the subacute stage. Compared with enhanced CT, MR using Gd-DTPA demonstrated more obvious enhancement of infarcted areas. MR enhancement using Gd-DTPA showed a gradual increase and the accumulated Gd-DTPA in infarcted areas slowly diffused to the periphery. MR enhancement with Gd-DTPA is similar to that of enhanced CT, but may be more sensitive in the detection of blood brain barrier breakdown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341737
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  • 10
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of the normal carotid bifurcation (1987)
    Springer
    Neuroradiology 29 (1987), S. 7-9 
    Details
    ISSN: 1432-1920
    Keywords: Carotid artery ; Magnetic resonance imaging ; Blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A Siemens 0.5 Tesla Magnetic Resonance Imaging (MRI) system was used with the saddle head coil and transverse scout localization for imaging 10 normal cervical carotid artery bifurcations in the sagittal plane. Good to excellent visualization of the flow voids and vessel contours was accomplished in all cases. Careful technique and patient cooperation are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341028
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  • 11
    Electronic Resource
    Electronic Resource
    Preliminary experience of magnetic resonance imaging in neurosarcoidosis (1987)
    Springer
    Neuroradiology 29 (1987), S. 127-129 
    Details
    ISSN: 1432-1920
    Keywords: Brain, diseases ; Brain, white and gray matter ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve MR scans performed on seven patients with neurosarcoidosis are presented. The most common abnormalities were ventricular enlargement (four patients) and diffuse periventricular white matter changes (three patients). Infarcts were seen in three patients and mass lesion in one. The lesions were seen in both T1 and T2 weighted images. The results are compared with CT findings. MRI seems to be more sensitive than CT in detecting white matter changes and infarcts. Ventricular enlargement and granulomas were equally well seen with both modalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327536
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  • 12
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in temporal bone fracture (1987)
    Springer
    Neuroradiology 29 (1987), S. 246-251 
    Details
    ISSN: 1432-1920
    Keywords: Temporal bone abnormalities ; Fracture skull base ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In seven patients with temporal bone fractures examined by both CT and MRI, thin section CT proved superior to MRI in demonstrating the full extent of the fractures and the status of the ossicular chain. MR studies were able to demonstrate fractures, when these fractures contained blood or CSF, and the presence of ossicular dislocation in one case where the middle ear was completely filled with CSF or blood. Admixture of air in the middle ear gave a false impression of ossicular dislocation, while air in the fracture obscured portions of it. MR proved superior to CT in the evaluation of intracranial contents by showing 5 additional subdural hematomas, 2 epidural hematomas and 2 hemorrhagic contusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451761
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  • 13
    Electronic Resource
    Electronic Resource
    Intracranial catecholamine secreting paragangliomas (1987)
    Springer
    Neuroradiology 29 (1987), S. 277-282 
    Details
    ISSN: 1432-1920
    Keywords: Paraganglioma ; Catecholamines ; Glomus jugulare ; Sphenopalatine ganglion ; Computed tomography ; Magnetic resonance imaging ; Angiography ; Embolisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three intracranial catecholamine-secreting paragangliomas are described. They involved a glomus jugulare, a sphenopalatine ganglion and the clivus and upper cervical spine respectively. The extent of the tumours was shown by CT and MRI. They were all highly vascular with a substantial blood supply from systemic arteries which was subjected to particulate embolisation, followed in two cases by surgery. The importance of studying any tumour which could possibly be a paraganglioma for hormonal and, especially, for catecholamine secretion prior to any invasive procedure, including angiography and embolisation, is emphasised: all such procedures should be covered with catecholamine blocking agents and, in addition, carefully monitored with resuscitation facilities immediately available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451767
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  • 14
    Electronic Resource
    Electronic Resource
    Invasive v non-invasive assessment of the carotid arteries prior to trans-sphenoidal surgery (1987)
    Springer
    Neuroradiology 29 (1987), S. 457-461 
    Details
    ISSN: 1432-1920
    Keywords: Trans-sphenoidal hypophysectomy ; Cavernous sinography ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Imaging studies in 47 patients who were to undergo trans-sphenoidal surgery were analysed with reference to the vascular structures in the parasellar region. The results of cavernous sinography, dynamic contrast enhanced Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) showed good correlation with each other and with the appearances found at operation. CT and MRI, both non-invasive investigations, are therefore reliable preliminary screening methods for identifying the small proportion of patients on whom other imaging techniques need to be performed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341743
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  • 15
    Electronic Resource
    Electronic Resource
    Topological characteristics of brainstem lesions in clinically definite and clinically probable cases of multiple sclerosis: an MRI-study (1987)
    Springer
    Neuroradiology 29 (1987), S. 530-534 
    Details
    ISSN: 1432-1920
    Keywords: Multiple scleosis, diagnosis of ; Magnetic resonance imaging ; Vascular brain disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Disseminated lesions in the white matter of the cerebral hemispheres and confluent lesions at the borders of the lateral ventricles as seen on MRI are both considered acceptable paraclinical evidence for the diagnosis of multiple sclerosis. Similar changes are, however, also found in vascular diseases of the brain. We therefore aimed at identifying those additional traits in the infratentorial region, which in our experience are not frequently found in cerebrovascular pathology. We evaluated MR brain scans of 68 patients and found pontine lesions in 71% of cases with a clinically definite diagnosis (17 out of 24) and in 33% of cases with a probable diagnosis (14 out of 43). Lesions in the medulla oblongata were present in 50% and 16%, respectively, and in the midbrain in 25% and 7%, respectively. With rare exceptions all brainstem lesions were contiguous with the cisternal or ventricular cerebrospinal fluid spaces. In keeping with post-mortem reports the morphological spectrum ranged from large confluent patches to solitary, well delineated paramedian lesions or discrete linings of the cerebrospinal fluid border zones and were most clearly depicted from horizontal and sagittal T2 weighted SE-sequences. If there is a predilection for the outer or inner surfaces of the brainstem, such lesions can be considered an additional typical feature of multiple sclerosis and can be more reliably weighted as paraclinical evidence for a definite diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350435
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  • 16
    Electronic Resource
    Electronic Resource
    Remote metabolic effects of cerebrovascular lesions: magnetic resonance and positron tomography imaging (1987)
    Springer
    Neuroradiology 29 (1987), S. 1-6 
    Details
    ISSN: 1432-1920
    Keywords: Positron emission tomography ; Magnetic resonance imaging ; Cerebrovascular disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Combined Positron Emission Tomography (PET) and Proton Magnetic Resonance Imaging (MRI) study were performed in six patients with chronic supratentorial stroke to investigate whether remote hypometabolic regions revealed by PET showed any abnormality on MRI. Either regional oxygen consumption (n=4) or glucose utilization (n=2) were measured using PET and the 15O steady state 18FGD technique, respectively. Four patients, with deeply located brain lesions, showed a significant metabolic reduction in the overlying cerebral cortex. In the remaining two patients, affected by a large cortical infarct, there was a significant crossed cerebellar hypometabolism. The MRI weighted by the parameters spin density (ϱ), spin lattice (T1) and spin-spin (T2) relaxation times were obtained employing various sequences in the same subjects. In no patient did the MRI show any contrast modification in these hypometabolic remote regions, suggesting that subtle loss of tissue and/or biochemical change do not underlie the reduction in metabolic rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341027
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  • 17
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in Pelizaeus-Merzbacher disease (1987)
    Springer
    Neuroradiology 29 (1987), S. 403-405 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Pelizaeus ; Merzbacher disease ; Cerebral sclerosis diffuse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pelizaeus-Merzbacher's disease is a progressive encephalopathy with demyelination of the cerebral white matter. The diagnosis can not be made on clinical or biological grounds: pathological investigation is necessary to confirm tigroid demyelination. CT scanning failed to visualize this type of anomaly but detection is now possible with the advent of magnetic resonance imaging (MRI). The authors studied the case of a boy who, at the age of 8 presented with symptoms characteristic of the disease: rotatory nystagmus, progressive encephalopathy, and inherited X-linked recessive traits. Magnetic resonance imaging revealed a high signal in the supra-tentorial white matter and the usual contrast was inverted. The authors believe that MRI can make an important contribution to the diagnosis of the disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348925
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  • 18
    Electronic Resource
    Electronic Resource
    The role of magnetic resonance imaging in giant cell tumor of bone (1987)
    Springer
    Skeletal radiology 16 (1987), S. 635-643 
    Details
    ISSN: 1432-2161
    Keywords: Giant cell tumor ; Bone neoplasms ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In six cases of giant cell tumor the magnetic resonance (MR) images obtained with various pulse sequences and field strengths were compared to the corresponding computed tomography (CT) scans and plain roentgenograms. MRI was superior to CT and plain films in demonstrating areas of tissue inhomogeneity within the tumor as well as soft tissue extension. CT was superior in demonstrating cortical thinning. Multiplanar imaging capability and visualization of articular cartilage may demonstrate intra-articular tumor spread. The characteristic MRI findings with short TR/TE (T1-weighting) and long TR/TE (T2-weighting) are described. We also describe one case where serial MR scans were used to assess response to therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357112
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  • 19
    Electronic Resource
    Electronic Resource
    The magnetic resonance imaging appearance at 1.5 Tesla of cartilaginous tumors involving the epiphysis (1987)
    Springer
    Skeletal radiology 16 (1987), S. 647-651 
    Details
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Bone neoplasms ; Chondroblastoma ; Clear cell chondrosarcoma ; Iliopsoas bursa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three cases of lytic, calcified epiphyseal lesions with plain film and computed tomography features suggestive of chondroblastoma were imaged by magnetic resonance imaging. Histopathologic correlation was obtained in each case. Two cases of chondroblastoma showed low signal intensity on both short (TR600/TE20ms) and long (TR2500/TE80ms) spin echo (SE) images. The third case, a clear cell chondrosarcoma, demonstrated increased signal intensity on moderately T2 weighted (TR2500/TE40ms) images. These findings suggest that magnetic resonance imaging may be helpful in distinguishing these lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357114
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  • 20
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of osteosarcoma (1987)
    Springer
    Skeletal radiology 16 (1987), S. 23-29 
    Details
    ISSN: 1432-2161
    Keywords: Osteosarcoma ; Magnetic resonance imaging ; Pulsing sequences ; Appearances and clinical value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Early magnetic resonance (MR) experience in the evaluation of 14 consecutive long bone intramedullary osteosarcomas demonstrates the need for T1 and T2 weighted pulsing sequences in the staging of this disease. Intramedullary disease is best depicted by coronal T1 weighted pulsing sequences and subtle extra-compartmental discase by T2 weighted axial imaging. Both high intensity and low intensity intra-medullary signals were noted on T2 weighting, while all T1 weighted pulsing sequences showed intra-medullary disease to have low signal intensity. Extraosseous tumor on T2 weighting usually had a high signal, and disease extent was therefore sharply demarcated from uninvolved muscle and its relationship to vessels confidently assessed. MR appears optimally suited for local staging of osteosarcoma, further enhancing the role of radiology in planning limbsalvage surgical techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349924
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  • 21
    Electronic Resource
    Electronic Resource
    Soft tissue pseudotumor following intramuscular injection of “DPT”: a pitfall in magnetic resonance imaging (1987)
    Springer
    Skeletal radiology 16 (1987), S. 469-473 
    Details
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Soft tissues, magnetic resonance studies ; Muscles, neoplasms ; Juvenile fibromatosis, magnetic resonance studies ; Sedation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the time-dependent magnetic resonance imaging (MRI) changes that resulted from an intramuscular injection of a commonly-used pediatric sedation regimen (“DPT”). These changes at the site of injection consist of a focal abnormality characterized by a slight increase in signal intensity on T1 weighted images and markedly increased signal intensity on T2 weighted images. Alterations in signal are detectable almost immediately after the injection and progress over the first 31 hours. This abnormality, which could be mistaken for real disease, persists up to 36 days following injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350542
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  • 22
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    Magnetic resonance imaging in lissencephaly (1987)
    Springer
    European journal of pediatrics 146 (1987), S. 205-208 
    Details
    ISSN: 1432-1076
    Keywords: Lissencephaly ; Agyria ; Pachygyria ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In a patient with clinical manifestations suggestive of brain malformation, computer-assisted tomography (CT) showed lissencephaly: agyria, pachygyria, absent opercularization, and colpocephaly. The patient did not have seizures or a typical EEG of hypsarrhythmia. By magnetic resonance imaging (MRI), using a long inversion-recovery sequence, it was possible to verify the CT-findings and to demonstrate heterotopic grey matter and missing claustrum. By MRI it was much easier to estimate the altered ratio of grey and white matter. High grey-white matter contrast of inversion-recovery scans and the possibility of imaging the brain in sagittal, coronal and transverse planes make MRI the method of choice for the evaluation of lissencephaly and other brain malformations. In this case it helped to verify lissencephaly as one aspect of an unknown clinical entity of type-I-lissencephaly, defective structure of lymphatic nodes, a polyarthritis-like clinical picture, hypodontia, and flaring of the ribs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02343238
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  • 23
    Electronic Resource
    Electronic Resource
    Management of the intra-abdominal testis (1987)
    Springer
    European journal of pediatrics 146 (1987), S. 49-50 
    Details
    ISSN: 1432-1076
    Keywords: Intra-abdominal testis ; Localization ; Orchiopexy ; Laparoscopy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A survey was made of 30 pediatric urologists for their current practice. Localization, important for operative approach, is done by venography and arteriography; ultrasonography, computed tomography and magnetic resonance imaging; and laparoscopy, the last most often immediately before operation. The preferred operation is the long-loop was orchiopexy; two-stage orchiopexy and microsurgical autotransplantation are alternatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00452873
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  • 24
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    Spinal epidural lipomatosis: report of a case secondary to hypothyroidism and review of literature (1987)
    Springer
    Journal of neurology 234 (1987), S. 172-176 
    Details
    ISSN: 1432-1459
    Keywords: Spinal epidural lipomatosis ; Hypothyroidism ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Epidural lipomatosis usually occurs as a complication of steroid therapy. This report includes the first description of a case secondary to hypothyroidism. Adults in all age groups can be affected and present with progressive signs and symptoms of spinal cord or cauda equina compression. The dorsal aspect of the thoracic spine is most commonly involved, usually in its total extent. Spine radiographs are normal and myelography poorly delineates the nature and extent of abnormality. While computed tomography can provide information about the nature of the spinal mass, magnetic resonance imaging is the investigation of choice. Extensive decompressive laminectomy is useful but the results are variable. Correction of underlying endocrine abnormality can reverse the process. The need for early diagnosis of this disorder is therefore emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314138
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  • 25
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    Progressive multifocal leucoencephalopathy with magnetic resonance imaging verification and therapeutic trials with interferon (1987)
    Springer
    Journal of neurology 234 (1987), S. 427-429 
    Details
    ISSN: 1432-1459
    Keywords: Progressive multifocal leucoencephalopathy ; Magnetic resonance imaging ; Interferon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Progressive multifocal leucoencephalopathy was diagnosed by magnetic resonance imaging (MRI) and brain biopsy in a 44-year-old woman, for whom therapeutic trials with various antiviral agents were made. Despite early diagnosis and treatment, her neurological deterioration and extension of MRI-detectable lesions were not halted for a period of about 8 months. After the introduction of intrathecal β-interferon therapy, her neurological status and MRI findings became stable and showed minimal improvement. Early diagnosis of this fatal disorder is important and intrathecal interferon therapy should be considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314091
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  • 26
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    Electronic Resource
    Preoperative diagnosis of Rathke's cleft cyst (1987)
    Springer
    Child's nervous system 3 (1987), S. 225-227 
    Details
    ISSN: 1433-0350
    Keywords: Rathke's cleft cyst ; Suprasellar cyst ; Pituitary cyst ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two cases of Rathke's cleft cyst are presented. The cysts showed as high-density lesions on plain CT with slight enhancement with contrast medium. They appeared as a hyperintense mass in the T1-weighted magnetic resonance images. Preoperative diagnosis is very important because different sellar cystic lesions require different treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00274052
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  • 27
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    Electronic Resource
    High-resolution magnetic resonance imaging of the wrist: normal anatomy (1987)
    Springer
    Skeletal radiology 16 (1987), S. 128-132 
    Details
    ISSN: 1432-2161
    Keywords: Wrist ; Magnetic resonance imaging ; Surface coil ; Normal anatomy ; Cadaveric correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance imaging (MRI) provided adequate depiction of carpal soft tissue structures in normal volunteers, as well as accurate anatomic correlation with cadaveric specimens. Using a high field strength system and surface coil techniques, the intricate anatomy of the wrist was best defined on long TR short TE images. However, from a practical view, T1 weighted images (TR 600 ms, TE 25 ms) were most useful because of short imaging times, satisfactory image quality, and the absence of motion artifacts. The coronal plane provided the clearest definition of important structures. Potential diagnostic limitations exist due to the inability of MRI ot clearly delineate articular cartilage, joint capsules, and small interosseous ligmaents. The presence of intra-articular fluid in both living subjects and cadaveric specimens, however, allowed for fine depiction of these structures on T2 weighted images.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367760
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  • 28
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    An unusual case of central nervous system vasculitis (1987)
    Springer
    Journal of neurology 234 (1987), S. 344-347 
    Details
    ISSN: 1432-1459
    Keywords: CNS vasculitis ; Small vessel ; Recurrent cerebral bleeding ; Magnetic resonance imaging ; Immunosuppressive therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A patient with CNS vasculitis limited to small vessels is described. Initial spinal cord involvement with paraparesis was followed by multifocal cerebral and cerebellar involvement, depicted by magnetic resonance imaging (MRI). She also had recurrent cerebral bleeding. A diagnosis of vasculitis was made by cerebral biopsy. Immunosuppressive therapy resulted in clinical improvement and resolution of the MRI abnormalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314293
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  • 29
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    Evaluation by MRI of paraparesis and tetraparesis of undiagnosed aetiology (1987)
    Springer
    Journal of neurology 234 (1987), S. 401-407 
    Details
    ISSN: 1432-1459
    Keywords: Multiple sclerosis ; Tetraparesis ; Paraparesis ; Spinal tumour ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The clinical, neuroradiological, electrophysiological and CSF findings of seven patients with slowly progressive paraparesis or tetraparesis are presented. In all patients, the results of the tests performed, including evoked potentials, CT scanning, oligoclonal bands in the CSF and myelography, were normal or inconclusive and did not lead to the correct diagnosis of the aetiology. In contrast, magnetic resonance imaging (MRI) provided the diagnosis of the causative process: multiple sclerosis in four cases, meningioma of the craniocervical junction or upper thoracic spinal cord in two cases, and upper cervical cord low-grade astrocytoma in one case. The patients with tumour could be treated effectively. Without MRI, however, the correct diagnosis would have been delayed. T2-weighted spin-echo scans provided maximal sensitivity for the detection of MS plaques, although they lacked specificity for a special disease. Several morphological criteria during MRI were helpful in differentiating Binswanger's disease, leucodystrophy and adrenoleucodystrophy from MS. It is concluded that at present MRI is the only non-invasive test with which to screen reliably the craniocervical junction and the upper cervical level, both of which are diagnostically difficult regions. The case histories also demonstrate that MRI is essential in all patients where a full clinical evaluation of the suspected spinal segment is not possible. “Pure spinal MS” is a misleading diagnosis and should not be accepted without confirmation by MRI. MRI has to be performed early enough to permit timely treatment of spinal and brain-stem disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314085
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  • 30
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    Syringomyelic syndrome: clinical features in 31 cases confirmed by CT myelography or magnetic resonance imaging (1987)
    Springer
    Journal of neurology 235 (1987), S. 26-30 
    Details
    ISSN: 1432-1459
    Keywords: Syringomyelia ; Syringomyelic syndrome ; Metrizamide CT myelography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The clinical features of 31 cases of syringomyelic syndrome, confirmed by metrizamide CT myelography (CTM) or magnetic resonance imaging (MRI), were analysed. Bilateral suspended sensory disturbance, previously regarded as a characteristic feature, was encountered in only 2 cases (6.5%). Thirteen patients (41.9%) showed no motor deficits of the upper limbs and 7 patients (22.6%) did not have weakness or atrophy in any of the four extremities. Cervical segmental signs were absent in 7 cases (22.6%) and in 2 (6.5%) signs were only present in the lower limbs. Scoliosis and foot deformity, such as pes cavus or equinovarus, were seen in 17 (54.8%) and 5 cases (16.1%) respectively. These skeletal abnormalities were initial symptoms in some childhood cases. In syringomyelic syndrome, clinical features are variable with many atypical clinical manifestations, apart from the previously recognized characteristic clinical features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314193
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  • 31
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    Contribution of MRI in the diagnosis of haemangioblastomas (1987)
    Springer
    Journal of neurology 235 (1987), S. 95-98 
    Details
    ISSN: 1432-1459
    Keywords: Haemangioblastoma ; Magnetic resonance imaging ; Gadolinium-DTPA ; Angio-MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Magnetic resonance imaging (MRI) patterns of 11 haemangioblastomas examined with a 1.5-T scanner are described. MRI was as effective as contrast-enhanced CT in the detection of vascular tumour components, but was less sensitive than angiography. MRI was superior to CT in delineating the exact extent of the lesions, for example contact with the arachnoid surface. Even if a cystic tumour component is absent, MRI can provide helpful criteria for differential diagnosis; in particular, T2 values allow differentiation from meningiomas. In three patients additionally administered gadolinium (Gd) diethylenetriaminepenta-acetic acid (DTPA) the angiomatous parts of the tumour showed a remarkable decrease in T1 value, but the time dependence of the enhancement was not the same as that seen in dynamic CT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00718017
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  • 32
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    348. Zur diagnostischen wertigkeit der kernspintomographie im Bereich der aortenchirurgie (1987)
    Springer
    Langenbeck's archives of surgery 372 (1987), S. 952-952 
    Details
    ISSN: 1435-2451
    Keywords: Magnetic resonance imaging ; Aortic aneurysms ; Dissections ; Kernspintomographie ; Aortenaneurysmen ; Dissektionen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Um die diagnostische Wertigkeit der Kernspintomographie (KST) im Bereich der Aortenchirurgie zu überprüfen, wurden 47 Untersuchungen (22 prä-, 25 postoperativ) bei 28 Patienten mit aortalen Aneurysmen und Dissektionen durchgeführt. Präoperativ konnte die Grösse des Aneurysmas, intramuraler Thrombus, perivasculäre Strukturen, assoziierte Prozesse grösserer Gefässabgänge dargestellt werden. Nachweis einer Dissektion und Differenzierung von wahren und falschen Lumen war immer möglich. Postoperativ wurde das Operationsergebnis dokumentiert und die KST als Verlaufskontrolle eingesetzt. Aufgrund der hohen räumlichen Auflösung in jeder gewünschten Schnittebene, der Nichtinvasivität, der Vermeidung von Röntgenstrahlen und Kontrastmittel stellt die KST eine wertvolle Erweiterung des diagnostischen Instrumentariums für den Bereich aortaler Erkrankungen dar.
    Notes: Summary For diagnostic evaluation of magnetic resonance imaging (MRI) of aortic disease, 47 examinations (22 pre-, 25 postoperatively) were performed in 28 patients with aortic aneurysms and dissections. Preoperatively, the extent of the aneurysm, intramural thrombus, perivascular structures, and associated process of major side branches could be documented. Diagnosis of dissection and differentiation of true and false lumen were always possible. Postoperatively, the operative result could be imaged and MRI was used for follow-up. As there is a high spatial solution in every section desired, non-invasiveness, and no X-rays or contrast material, MRI is a valuable enrichment to the diagnostic armamentarium of aortic pathology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298133
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    Extracranial chondroma of the skull base (1987)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1987), S. 424-428 
    Details
    ISSN: 1434-4726
    Keywords: Chondroma ; Skull base ; Nasopharynx ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report a case of an extracranial chondroma of the skull base. This tumor occupied mainly the skull base, the nasopharynx and the parapharyngeal space. Magnetic resonance imaging was effective in diagnosis and determining the extent of the lesion. Total extirpation of the lesion was performed via an external cervical approach. A survey of the available literature revealed only three similar cases treated to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464656
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  • 34
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 1. A Study of Bimolecular Nucleophilic Substitution at the Boron Atom (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 499-510 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetradentate ligand 2,2′,2″-nitrilotriphenol forms a boron complex III with an intramolecular, transannular N→B dative bond of 1.68 Å in a strained tricyclo[3.3.3.0]undecane chelating system. The complex reacts with nitrogen bases L, such as pyridine, quinuclidine and others, to form complexes III-L, in which the intramolecular B-N bond is replaced by one between B and the external nucleophile. In solution, this displacement reaction is reversible. It was studied by temperature-dependent NMR spectroscopy. The resulting reaction and activation parameters suggest that the reaction is a bimolecular nucleophilic substitution (SN2).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700303
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  • 35
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 3. Crystal and Molecular Structures of Three Aluminium Complexes (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 520-533 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal and molecular structures of three Al(III) complexes of the tripod ligand 2,2′,2″-nitrilotriphenolate (I) are presented. They all show 5-coordinate Al in approximately trigonal bipyramidal geometry, with an external nucleophile X occupying the second axial position. X is OH- in[Al(I)(OH)]-[Hquin]+ (quin = quinuclidine), N in [Al(I)(py)] (py = pyridine), and one of the O-atoms of a second molecule in the dimeric [(Al(I))2]. Correlated variations in the axial bond lengths of the trigonal bipyramid are observed: [(Al(I))2]: Al-Nint. = 2.094 Å, Al-Oext. = 1.850 Å; [Al(I)(py)]: Al-Nint. = 2.153 Å, Al-Next., = 1.992 Å; [Al(I)(OH)]-: Al-Nint. = 2.278 Å, Al-Oext. = 1.765 Å. They are interpreted in terms of a dissociative reaction path at the Al(III) centre.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700305
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  • 36
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    Molluscicidal Saponins from Swartzia madagascariensis DESVAUX (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 570-576 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phytochemical investigation of the dried fruits of Swartzia madagascariensis (Leguminosae) afforded the five triterpenoid saponins 1-5. They were shown to be glucuronides of oleanolic acid and of gypsogenin by chemical and spectral means (FAB-MS, 13C-NMR, GC/MS). One of the isolated compounds, identified as 3-O-[O-α-L-rhamnopyranosyl-(1→3)-(β-D-glucopyranosyluronic acid)]oleanolic acid, was responsible for the high molluscicidal activity of Swartzia madagascariensis fruits against the schistosomiasis-transmitting snails Biomphalaria glabrata and Bulinus globosus.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700309
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  • 37
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    The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 587-592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8. In contrast, porcine liver esterase (PLE, EC 3.1.1.1) cleanly hydrolyses 5 to give the isolable 1-methyl-2,4-cyclopentadiene-1-carboxylic acid (13). The latter undergoes thermal dimerization with conservation of the geminal-substitution pattern. The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C2 symmetry. Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acid concentration is used. The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700311
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    Potassium Carboxylates by Direct Carbonylation of Potassium Alkoxides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 593-599 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the K+ alkoxide of linalool (1) in benzene with CO at 425-440 bar and 120-130° for 12-30 h gave the K+ salt of 2,6-dimethyl-2-vinyl-5-heptenoic acid (4a) in a ca. 25% yield based on ca. 65% converted alkoxide. Reaction of the [K+ ⊂ 18-crown-6] alkoxide of 1 with CO at 50-55 bar and 40° for 90-140 h gave a mixture containing mainly the [K+ ⊂ 18-c-6] salts of 4a (ca. 62%) and of the homogeranic acids 3a and 6a (together ca. 27% of the mixture) in a ca. 35% combined yield based on 50-60% converted alkoxide. The uncomplexed or complexed K+ alkoxide of (S)-1 gave, with ca. 85% net retention, the K+ salt of (S)-4a. Reaction of the [K+ ⊂ 18-c-6] alkoxide of geraniol (2) with CO at 50 bar and 40° for 65-70 h gave myrcene (10) and geranyl formate (11) in a ca. 40-50% yield each based on ca. 85% converted alkoxide. Reaction of the [K+ ⊂ 18-c-6] alkoxide of 3-pentyl-1,4-pentadien-3-ol (14) at 50 bar and r.t. for 70 h gave a mixture of the [K+ ⊂ 18-c-6] salts of 2-pentyl-2-vinyl-3-butenoic acid (15a) (67%) and the 4-pentyl-2,4-hexadienoic acids 18a and 19a (together 23% of the mixture) in a ca. 90% combined yield based on ca. 65% converted alkoxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700312
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    Synthesis and Copper(I) Complexes of a Series of 9- to 13-Membered N3 Macrocycles (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 680-689 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight cyclic triamines with ring sizes between 9 and 13 were synthesized by the p-toluenesulfonate method. The open-chain triamines bis(2-aminoethyl)amine (dien) and bis(3-aminopropyl)amine (diprop) were used as starting materials. In some cases, the corresponding dimeric cyclic hexaamines have been isolated and characterized as major by-products. The complexation of Cu(I) by the triamines has been studied potentiometrically in CH3CN/H2O. All ligands L form ternary complexes [Cu(CH3CN)L]+. The corresponding association constants vary between 1011 and 107, decreasing with increasing ring size. In addition, complexes [Cu(CH3CN)yLH]2+, y = 1 or 2, are found as less important species with maximum concentrations of 7 to 50%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700318
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    The Microstructure of Selective Palladium Hydrogenation Catalysts Supported on Calcium Carbonate and Modified by Lead (Lindlar Catalysts), Studied by Photoelectron Spectroscopy, Thermogravimetry, X-Ray Diffraction, and Electron MicroscopyThe following abbreviations and acronyms are used in the text: B. e. : Binding energy [eV], BET: Brunauer-Emmett-Teller (method of surface-area determination by physisorption of N2), AES: Auger electron spectroscopy, XPES: X-ray photoelectron spectroscopy, UPES: Ultraviolet photoelectron spectroscopy, ISS: Ionscattering spectroscopy, UHV: Ultrahigh vacuum (10-5 Pa), FTIR: Fourier-transform IR spectroscopy, TGA: Thermal gravimetric analysis, XRD: X-ray diffraction, XDA: Energy dispersive microanalysis, SEM: Scanning electron microscopy, TEM: Transmission electron microscopy, FWHM: Full width at half maximum. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 627-679 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the system Pd + Pb on CaCO3 is presented. This system known as Lindlar catalyst is used for selective hydrogenations of C≡C bonds to C=C bonds. It was found to consist of seven distinct chemical phases. Essential ingredients are solid solutions of hydrogen and oxygen in Pd. The latter phase enables the metal particles to be attached to the support via an orientational relationship calcite (113)∥Pd + O (111). The addition of Pb neither changes the micromorphology of the disk-shaped Pd particles nor does it modify the electronic structure of Pd as studied by chemisorption experiments. The addition of Pb seems to block certain active sites and, thus, to enhance the selectivity. The support was found to be a multi-domain mixture of calcite and aragonite with domain sites of several hundred Å. The free surface of the pore-free solid is covered by a calcium-hydroxide carbonate. This phase as well as several other Pb phases seem to represent only spectator materials. Verification of this as well as finding the correlation between structure and function of the various components requires a kinetic analysis which is outside the scope of this paper. It is demonstrated that a variety of analytical techniques is required to unravel the complex nature of such a ‘simple' catalyst’ as it is Pd on CaCO3.
    Additional Material: 36 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700317
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  • 41
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    Verapliquinones: Novel Diprenylquinones from an Aplidium sp. (Ascidiacea) of Ile-Verte Waters, Brittany (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 621-626 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Aplidium sp. (Ascidiacea), collected in French Atlantic waters near the Ile Verte, is shown to contain verapliquinone B (2) and verapliquinone D (6) as the first examples of linear diprenylquinones of the neryl type, besides their respective isomers 1 and 5 of the geranyl type.
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    Fe(II)-Induced Fragmentation Reaction of γ-Hydroperoxy-α,β-enones. Part 1. Synthesis of 13(14→8)-abeo-Steroids (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 701-716 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some steroidal analogues embodying the hitherto unknown 13(14→8)-abeo skeleton have been synthesized by Fe(II)-induced rearrangement (tandem β-fission/reductive alkylation) of 14α-hydroperoxy-7-en-6-ones. The configurational assignment was made by thorough analysis of NMR spectra; the structure of one of the products was unambiguously assessed by X-ray single-crystal analysis.
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  • 43
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    Light-Induced, Thermal, and Acid-Catalyzed π-Skeletal Rearrangements of Five-Ring-Annelated HeptalenesPresented in part by H.-J.H. in a lecture at the ETH in Zürich, 1985. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 742-759 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that, upon irradiation in CDCl3 solution, 5,6,8,10-tetramethylheptalene-1,2-dicarboxylic anhydride (6) rearranges to its double-bond-shift (DBS) isomer 7 in an equilibrium reaction (Scheme 2). The isomer 7 is DBS stable at -50°. At ca. 30°, a thermal equilibrium with 97.8% of 6 and 2.2% of 7 is rapidly established. Similarly, the ‘ortho’-anhydrides 9 and 11 (Schemes 4 and 5) can be rearranged to their corresponding DBS isomers 12 and 13, respectively. Whereas 12 is DBS stable at 30° (at 100° in tetralin, 94.0% of 9 are in equilibrium with 6.0% of 12), the i-Pr-substituted isomer 13 is already at 30° in thermal equilibrium with 11 leading to 98.7% of 11 and 1.3% of 13. It is shown by rearrangement of diasteroisomeric ‘ortho’-anhydrides of known relative and absolute configuration (Scheme 6) that the DBS in such five-ring-annelated heptalenes occurs with retention of the configuration of the heptalene skeleton as already established for other heptalene compounds. It is found that the DBS process may also take place under acid catalysis (e.g. HCl/CH3OH), thus yielding 9 from 12 (Scheme 9). The ‘ortho’-anhydrides 21 and 23 (Scheme 10) which are isomeric with 9 and 11 (Scheme 3) undergo rapid DBS' already at room temperature. The thermal equilibrium 21⇄22 consists of 18% of 21 and 82% of 22 at 30° and that of 23⇄24 of 17% of 23 and 83% of 24 at -30°. From these equilibrium mixtures, the pure DBS isomer 22 can be obtained by crystallization. Again, these rapid DBS' occur with retention of configuration of the heptalene skeleton (Fig. 4).
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    Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-PhenylnonafulvenHerrn Prof. Dr. Hans Nitschmann zum 80. Geburtstag gewidmet52. Mitt. über Fulvene, Fulvalene; 51. Mitt. [1]; Kurzmitt. [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 862-880 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT-; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.
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    Field-Desorption Mass Spectra of Fern Phloroglucinols Containing Three to Six Ring ConstituentsDedicated to the late Prof. Peter Brown (12.IX.1938-15.III.1981), Dept. of Chemistry, Arizona State University, Tempe, Arizona 08521, U.S.A., Whose premature death was a great loss to his friends and collegues. The last letter which we received from him (November 15, 1980) contained the first FD mass spectra of five relatively large fern phloroglucinols which he had successfully analyzed. Two of these spectra, in which no thermal rearrangement and /or fragmentation was observed, are reproduced in this article (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 881-893 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been previously shown that the structural analysis of the title compounds by electron-impact ionization (EI)mass spectrometry is complicated by extensive, if not complete, thermal rottlerone-type rearrangement and/or fragmentation reactions. The use of a ‘softer’ ionization technique such as field desorption (FD) is, therefore, required in order that these compounds may be characterized in terms of their molecular size and composition. In this report, the FD mass spectra of typical representatives of this class of compounds are described along with the attempted suppression of undesirable thermal reactions by the optimization of the emitter temperatures.
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    Structures and Electrical Properties of Some New Organic Conductors Derived from the Donor Molecule TMET (S,S,S,S,-Bis(dimethylethylenedithio) tetrathiafulvalene) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 942-953 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf-6, AsF-6, SbF-6, I-3 (incommensurate), and 3:2 with tetrahedral anions BF-4, CIO-4, ReO-4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.
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    Bildung tricyclischer Thietan-Derivate durch intramolekulare(2+2)-Cycloaddition (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 992-994 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Thietane Derivatives via Intramolecular (2+2) CycloadditionOn irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b, synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a,b, undergo an intramolecular (2+2)-cycloaddition reaction of the C=S and C=C bonds to give the tricyclic thietane derivatives 3a,b.
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    Photochemical Synthesis of 2-Alkylidene-1,3-cyclocalkanediones. Preliminary Communication (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 995-996 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis (λ = 254 nm) of 4-(tert-butyl)-4,6,7,8-tetrahydro-7,7-dimethy-2H-1-benzopyran-2,5(3H)-dione (3a) in t-BuOH affords 2-(2,2-dimethylpropylidene)-5,5-dimethyl-1,3-cyclohexanedione (1a) in 80% yield via homolysis of the lactone O—CO bond and subsequent ketene elimination.
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    Some Cyclic Oligopeptide with S2n Symmetry (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1012-1016 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some cyclic oligopeptides formed by an equal number of alternating D- and L-amino-acid residues have been synthesized by using the hydrochloride of the open-chain peptide acid as precursor and the mixed-anhydride condensation method. The cyclic oligopeptides (tetra-, hexa-, and octavaline, hexaleucine, and hexaphenylalanine) form very stable H-bonded structures (IR-amide band at 3270-3290 cm-1) which are insoluble in common organic solvents. In CF3COOH/CDCI3 (25°), they yield 1H-NMR spectra snowing the expected equivalency of the various amino-acid residues.
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    Strukturaufklärung ungewöhnlicher Umlagerungsprodukte von S-(1-Alkenyl)sulfoximiden mit Hilfe der Stossaktivierungsmassenspektrometrie (CAD-MS) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1041-1049 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure Determination of Unusual Rearrangement Products of S-(1-Alkenyl)sulfoximides by Collisionally Activated Dissoication Mass Spectrometry (CAD-MS)The Molecular ions of s-(l-alkenyl)--N-(p-tolyl)sulfoximides 1 are transformed into the N(phenylsufenyl)sulfonamides 3+ by a 1,2-migration of the alkenyle group to the O-atom of the sulfoximide function followed by a 2,3-sigmatropic rearrangement. The structure of the production e has been unambiguouslydetermined by the CAD method, showing the identity of the ion e (m/z368) obtained from 1a and from 4a.
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    Reaktionen von 1,2-Bis(trimethylsilyl)iminen mit Selen-und Tellur-halogeniden (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1076-1078 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 1,2-Bis(trimethylsilyl)imines with Selenium and Tellurium HalogenidesThe reactions of benzil-bis(trimethylsily)imine and phenanthrene-9,10-bis(trimethylsilyl)imine with SeOCl2, SeCl4 and TeCl4 are described.
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    Remote Tricarbonyl(diene)iron Substituent Effect on Ester Heterolysis. The Solvolyses of 5,6,7,8-Tetramethylidenebicyclo[2.2.2]oct-2-yl Methanesulfonate and of its Tricarbonyliron Mono- and Dinuclear ComplexesPart of Ph.D. thesis of J.-C. Zwick, Ecole Polytechnique Fédérale de Lausanne, 1987. Part of this work has been presented at the Fall Meeting of the Swiss Chemical Society in Bern, Oct. 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1079-1094 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Buffered acetolyses and hydrolyses of 5,6,7,8-tetramethylidenbicyclo[2.2.2]oct-2-yl methanesulfonate (17), of its ‘syn-endo’ (18), ‘syn-exo’ (19), ‘anti-endo’ (20), ‘anti-exo’ (21) tricarbonyliron complexes and of its ‘anti-exo,syn-endo’ (22) and ‘anti-endo,syn-exo’ (23) bis(tricarbonyliron) dinuclear complexes have been investigated (product analysis and kinetics). In contract with the solvolyses of the uncomplexed mesylate 17, the solvolyses of the complexed esters can be highly chemo- and stereoselective. The nature of the products (non-rearranged bicyclo[2.2.2]oct-2yl vs. rearranged bicyclo[3.2.1]oct-2-yl derivatives) depends on the relative configuration of the tricarbonyl(diene)iron moieties and on the medium. The rates of solvolyses of 17 are only slightly affected by complexation of one or both s-cis-butadiene units with Fe(CO)3 groups, except in the cases where the diene moiety ‘anti’ with respect to the mesylate is complexed onto its ‘endo’ face (20,23). In these cases, significant rate-retardation effects are observed, consistent with the inductive effect of the Fe(CO)3 substituent. Such retardation effects are overwhelmed by competing accelerating homoallylic participation by uncoordinated ‘anti’ -diene moieties (18,19) or, as in the case of the ‘anti-exo’-Fe(CO)3 complexes 21 and 22, by possible direct metal participation to the ionization process.
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    Synthetic Models of the Active Site of Cytochrome P-450. 1st Communication. The Synthesis of a Doubly-Bridged Iron(II)-Porphyrin Carrying a Tightly Bound Thiolate LigandPresented in part at the ‘Gordon Research Conference’ on the ‘Chemistry and Biology of Pyrroles’, New Hampshire, 27.7.-1.8.86 (W.-D.W.), and at the ‘Swiss Chemical Society’ meeting, Bern, 10.10.86 (B.S.). (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1173-1193 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The doubly-bridged iron(II)-tetraphenylporphyrin derivative 6, carrying a sterically fixed S- ligand in the ‘proximal’ position and the substrate at the ‘distal’ site, was synthesised as an enzyme model for cytochrome P-450. Compound 36, the CO complex of 6, displays a split Soret band (403 and 457 nm) similar to the native cytochrome P-450.
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    Stereoselektive Alkylierung an C(α) von Serin, Glycerinsäure, Threonin und Weinsäure über heterocyclische Enolate mit exocyclischer DoppelbindungZughörige Kurzmitteilungen: [1] (Weinsäre) [2] (Threonin) [3] (Serin) [4] (Glycerinsäure).Siehe auch die Diskussionen in den vor kurzem erschienenen Übersichtsartikeln [5][6]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1194-1216 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steroselective Alkylation at C(α) of Serine, Clyceric Acid, Threonine, and Tartaric Acid Involving Heterocyclic Enolates with Evocyelic Double BondsThe chiral, non-racemic title acids are converted to methyl dioxolane-(cf. 13), oxazoline-(4) and oxazolidinecarboxylates (cf. 9). Deprotonation by Li(i-Pr) 2N at dry-ice temperature gives solutions of the lithium enolates A-D With exocyclic enolate double bonds. These are stable crough with respect to β-elimination (Scheme 1) to be alkylated with or without cosolvents such as HMPA or DMPU The products are formed in good to excellent yields and, with the exception of the tartrate-derived acetonlde (see Scheme 2), with diastereoselectivities above 90%. While the tartrate-and threonine-derived enolates (A and B, resp.) are chiral due to the second stereogenic center of the precursors, the serine- and glyceric-acid-derived enolates (Aand B, resp.) are chiral due to the second sterogenic center of the precursors, the serine-nd glyceric-acid-derived enolates are non-racemic due to a tert butyl-substituted (pivalaldehyde-derived) acetal center (C and D, resp.). The products of alkylation can be hydrolyzed to give α-branched tartaric acid (Scheme 2), allothreonine (Scheme 3), serine (Scheme 4), and glyceric-acid derivatives (Scheme 5) with quaternary stereogenic centers. The configurations of the products are determined by NOE-NMR measurements and by chemical correlation. These show that the dioxolane-derived enolates A and D are alkylated preferentially from that face of the ring which is already substituted (‘syn’-attack), while the dihydrooxazol-and oxazolidine-derived enolates B and C are alkylated from the opposite face (‘anti’-attack). The ‘syn’-attack is postulated to arise from strong folding of the heterocyclic ring due to electronic repulsion between the enolate π-system and non-bonding electron pairs on the heteroatoms (see Scheme 6).
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    Novel Synthesis of Agaritine, a 4-Hydrazinobenzyl-Alcohol Derivative Occurring in Agaricaceae (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1261-1267 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 4-hydrazinobenzyl alcohol (3 was prepared (58%)) by diiobutylaluminiumhydride reduction of methyl 4-hydrazinobenzoate (4), whereas LiA1H4 or LiBh4 reduction of4 proceeded further to yield (via intermediate 3) (4-tolyl)hydrazine (5). The alcohol 3 was stable under O2-free conditions and exhibited no tendency to eliminate H2O, neither thermally nor with H+ catalysis. Oxidation of 3 with SeO2 yielded 4-(hydroxymethyl)benzine-diazonium ion (8), identified by its azo coupling product 9 with 2-naphthol. Condensation of 3 with 1-benzyl 5-Hydrogen N-(benzyloxycarbonyl)-L-glutamate (10) in presence of dicyclohexylcarbodiimide afforded 81% of N2-(benzyloxycarbonyl)-L- glutamic acid 1-(benzyl-ester) 5-{2-[4-(hydroxymethyl)phenyl]hydrazide} (11) which upon controlled hydrogenolysis (quinoline-sulfur-poisoned Pd/C catalyst) gave 82% of L-Glutamic acid 5-{2-[4-(hydroxymethyl)phenyl] hydrazide} (1), i. e. agaritine, a metabolite of Agaricus bisporus. Without poisoning of the catalyst, hydrogenolysis of (11) yielded L-glutamic acid 5-[2-(4-tolyl)hydrazide] (12).
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    The Solid and Solution Conformations of (±)-Corycavine (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1482-1486 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of corycavine, a protopine-type alkaloid, has been determined by X-ray analysis. A conformational feature observed is the existence of a strong electrostade interaction between the N- and C-atom at a distance of 2.618 Å. Such an interaction stabilizes the 10-membered ring conformation of the structure. Analyses of NMR spectra indicate that corycavine has the same conformation in solution as in the crystal state.
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    Dimethylformamide-Exchange Mechanism on Some First-Row Divalent Transition-Metal IonsPart 33 of the series ‘High-Pressur NMR Study’. Part 32: [1].Taken in part from the diploma work of C. Cossy, Université de Lausanne, 1983.This work was presented in part at the 24th International Conference on Coordination Chemistry, Athens, Greece, August 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1516-1525 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of temperature on the dimethylformamide exchange on Mn(DMF)2+6 and Fe(DMF)2+6 has been studied by 13C- and 17O-NMR, respectively, yielding the following kinetic parameters: k298 equals; (2.2±0.2). 106 S-1, ΔH≠ = 34.6 ± 1.3 kJ mol-1, ΔS≠ = -7.4 ± 4.8 J K-1mol-1 for Mn2+ and K298 = (9.7 ± 0.2).105 S-1, Delta;H≠ = 43.0 ± 0.9 kJ mol-1, ΔS≠ = + 13.8 ± 2.8 J K-1mol-1 for Fe2+. The volumes of activation, ΔV≠ in cm3mol-1, derived from high-pressure NMR on these metal ions, together with the previously published activation volumes for Co2+ and Ni2+ (+2.4 ± 0.2 (Mn2+), +8.5 ± 0.4 (Fe2+) +9.2 ± 0.3 (Co2+), + 9.1 ± 0.3 (Ni2+)) give evidence for a dissociative activation mode for DMF exchange on these high-spin first-row transition-metal divalent ions. The small positive ΔV≠ value observed for DMF exchange on Mn2+ seems to indicate that a mechanistic changeover also occurs along the series, (probably from Id to D), as for the other solvents previously studied (Ia to Id, for H2O, MeOH, MeCN). This changeover is shifted to the earlier elements of the series, due to more pronounced steric crowding for dimethylformamide hexasolvates.
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    Two New Antifungal Naphthoxirene Derivatives and their Glucosides from Sesamum angolense WELW (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1551-1557 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two novel naphthoxirene derivatives 1 and 2 their glucosides 3 and 4 have been isolated from the root bark of Sesamum angolense Welw. (Pedaliaceae) by preparative liquid chromatography. The structure of 1 was established by X-ray diffraction analysis. The identities of the other naphthcxirenes were deduced by spectroscopic (IR, UV, 1H-NMR, 13C-NMR, EI-MS, DCI-MS) and chemical methods (oxidation, acid and enzymatic hydrolysis). Compounds 1-3 exhibited antifungal activity. Naphthoxirene 1 was, in addition, cytotoxic to human colon carcinoma cells.
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    On Negative Birefringence in Water-in-Oil Microemulsions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1531-1536 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The occurrence of a negative birefringence in water-in-oil (W/O) microemulsions has been substantiated and analyzed. The analysis is based on the well-established aqueous nanodroplet model of W/O microemulsions. In the particularly investigated water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/aliphatic oil systems, the AOT monolayer exhibits a negative induced intrinsic birefringence, which is brought about by the pronounced polarizability of the alkyl moiety of the AOT molecule approximately perpendicular to the direction of its permanent dipolement.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700610
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    Erratum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2246-2246 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700829
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2305-2306 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700830
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  • 62
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    Herstellung und Charakterisierung in Membranen von Ionophoren mit Selektivität fü Natrium-Ionen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 153-157 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Neutral Sodium-Selective Ionophores and their Characterization in Membrane ElectrodesDifferent ionopbores based on N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide (1) have been prepared by substitution of the aromatic ring carrying the ether O-atoms. Substituents of widely different electronegativity (CH3, CH3O, CHO, CN NO2, Br) do not relevantly influence the ion selectivity.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700119
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    Complexes of 3,3′-Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans-Spanning Bidenatate Chelates?? (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 158-170 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] (1) forms monomeric, trans-square-planar complexes MX2(1) (M = Ni, Pd, Pt; X = Cl-, Br- I-, and, in part, N3-, NCS-, CN-, NO3-) as well as Pt(H)Cl(1), Pt(H)Br(1), and RhCl(CO)(1). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl2(1)]2 and cis-[PtCl2(1)]n (mean value of n ≈ 4-5) 31P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl(1)·0.5 (CH3)2C=O·0.39 C6H12 (space group C2/c,a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 Å3, Z = 8) confirms the presence of three-coordinate Ag(I), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700120
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    Aza-2-dienes-1,3. Partie 5. Préparation de N-aminoimidazoles, 3H-pyrroles, triazolo[1,2,4][1,5-a]pyrazines et imidazo[1,2-a]pyrazines (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 187-195 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazinesNucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700123
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    Syntheses of Tetrahydrolipstatin and Absolute Configuration of Tetrahydrolipstatin and Lipstatin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 196-202 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipstatin (1), a natural product, and tetrahydrolipstatin (2) are pancreatic lipase inhibitors. Non-stereoselective and partially stereoselective syntheses of 2 are used to establish the absolute configuration of tetrahydrolipstatin and lipstatin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700124
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  • 66
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    Ring-Open Analogues of Adenine Nucleoside. Aminoacyl Derivatives of Cyclo- and Acyclo-Nucleosides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 219-231 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of acyclic analogues of ribo- and deoxyribonucleosides is described. These compounds (Table 3) are both poor substrates and poor inhibitors of adenosine deaminase. The synthesis of dinucleotides from these analogues is also described, and the activity along with the inhibitory properties of some of them are studied against deaminase enzyme. These nucleotides are resistant to degradation by phosphodiesterases. HCl impregnated on silica gel is an excellent reagent for the preparation of the chloromethyl ether precursors of acyclo-nucleosides. A general and rapid procedure is developed for the preparation and isolation of the 5′-aminoacyl derivatives of robo- and arabinonucleosides. Quinoline has a marked effect on aminoacylations without racemization. Compounds 35a, b possess remarkable antiviral effects in vitro. A procedure is also developed for the conversion of acyclo-ribonucliosides 13e, f to acyclo-deoxyribonucleosides 11e, f.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700127
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    Functionalisation of saturated hydrocarbons. Part 9Part 8:[1].. Oxidation of patchouli alcohol by the ‘gif system’: Isolation and organoleptic properties of three new ketonic derivativesDedicated to Prof. Vlado Prelog on the occasion of his 80th birthday (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 273-280 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of patchouli alcohol (1) using the ‘Gif system’ afforded as major isolated products three new ketonic derivatives 16-18. The structures of these compounds were established by spectral techniques including 2D-NMR. Ketones 16-18 display interesting organoleptic properties.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700202
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    Synthese von ω-(5-Oxo-1-cyclopentenyl)alkansäure-methylestern aus 2-Nitrocycloalkanonen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 315-320 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Methyl ω-(5-Oxo-1-cyclopentenyl)alkanoates Starting from 2-NitrocycloalkanonesA convenient synthesis of methyl ω-(5-oxo-1-cyclopentenyl)alkanoates 1 is described. 2-Nitrocycloalkanones 2 are converted to 2-(3,3-dimethoxypropy1)-2-nitrocycloalkanones 4. Treatment of 4 with MeOH/MeONa led to the ring-opened nitronates 5 which underwent a Nef reaction to form the corresponding oxo derivatives 6. Partial hydrolysis of followed by base-catalyzed aldol reaction gave the desired products in high yields.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700207
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    Cyclobut-2-enones from Alkynes via Dichlorocyclobut-2-enonesIn part taken from the Ph.D. thesis of A.A.A., University of Zürich, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 321-328 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [2 + 2]-cycloaddition of dichloroketene (prepared in situ from CCl3COCl and Zn(Cu)) with three alkynes 1a-c to form 2,3-dimethyl-(2a), 2,3-diethyl-(2b) and 3-butyl-4,4-dichlorocyclobut-2-enone (2c) proceeds rapidly in the absence of POCl3. The primary products 2a-c rearrange in situ to the 2,4-dichlorocyclobut-2-enones 3a-c under the influence of ZnCL2 produced during the reaction. ZnCl2 converts both 2a and 3a into a 4:6 equilibrium mixture of the two; this isomerization does not occur with LiCl. The Cl-atoms of both 2a, b and 3a, band of 2c may reductively be removed with Zn(Cu) in AcOH/pyridine to afford the alkylcyclobutenones 4a-c. Without pyridine, this reduction gives ca. 1:1 mixtures of the double-bond isomers 4 and 5 in low yields. The cyclobutenones 2c and 4c may be deuterated by CD3COOD in the presence of pyridine. D-Atom is introduced into 2c at C(4) and at C(γ), and into 4c at C(2) and C(4). A mechanism for this deuteration is considered, which does not involve a cyclobutadienolate 7, but rather a cyclobutenolate of type 8. The reductions of 2 and 3 to 4 might also pass through the same type of intermediate 8.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700208
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    3-(Dimethylamino)-2,2-dimethyl-2H-azirin als α-Aminoisobuttersäure(Aib)-Äquivalent: Cyclische Depsipeptide durch direkte Amid-CyclisierungVorläufige Mitteilung s. [1]; vgl. auch [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 329-338 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-(Dimethylamino)-2,2-dimethyl-2H,-azirine as an α-Aminoisobutyric-Acid (Aib) Equivalent: Cyclic Depsipeptides via Direct Amid CyclizationIn MeCN at room temperature, 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1) and α-hydroxycarboxylic acids react to give diamides of type 8 (Scheme 3). Selective cleavage of the terminal N,N-dimethylcarboxamide group in MeCN/H2O leads to the corresponding carboxylic acids 13 (Scheme 4). In toluene/PhSH, phenyl thioesters of type 11 are formed (see also Scheme 5). Starting with diamides 8, the formation of morpholin-2,5- diones 10 has been achieved either by direct amide cyclization via intermediate 1,3-oxazol-5(4H)-ones 9 or via base-catalyzed cyclization of the phenyl thioesters 11 (Scheme 3). Reaction of carboxylic acids with 1, followed by selective amide hydrolysis, has been used for the construction of peptides from α-hydroxy carboxylic acids and repetitive α-aminoisobutyric-acid (Aib) units (Scheme 4). Cyclization of 14a, 17a, and 20a with HCI in toluene at 100° gave the 9-, 12-, and 15-membered cyclic depsipeptides 15, 18, and 21, respectively.
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    URL: http://dx.doi.org/10.1002/hlca.19870700209
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    Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 369-374 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olidThe title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3a). The key step in this transformation is the isomerization of the C=C bond in 3a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid (11a), which, after hydrolysis and decarboxylation, gave 13a. In addition, the syntheses of five other compounds related to 13a are reported.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700214
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    Triaziridine 7. Mitteilung6. Mitteilung: [1].. Stabile pyramidale Konfigurationen an den Stickstoff-Atomen von Dialkyl-und Trialkyl-triaziridinen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 381-389 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl-and Trialkyl-triaziridinesStereochemical features of the recently synthesized nine samples of di- and trialkyl-triaziridines, namely the 1,3-cyclopentylen-(series a) and the two stereoisomers of the diisopropyl derivatives (series b and c), containing as the third substituent an H-atom (2), a CH3 group (3)or a CH2OH group (4), were elaborated on the basis of the 1H-, 13C-, and 15N-NMR spectra. The three N-atoms of the saturated N3-homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2-4 of the series a and b possess twofold symmetry (Cs), while 2-4 of series c are asymmetric. Thus, series c has the trans-configuration at N(2)/N(3) and, consequently, the cis-configuration at N(1)/N(2), while series a and b have the cis-configuration at N(2)/N(3) and -since the all-cis-arrangement is excluded-the trans-configuration at N(1)/N(2). The asymmetry of the trans-configurated 2c turned into twofold symmetry (C2), when a little CF3COOH was added. The 1H- and 13C-NMR data of series b and c of our alkyl-triaziridines exhibit a shielding effect, according to which there are two types of i-Pr groups, i-Pr(a) and i-Pr(b). They differ in the NMR signals of the H- and the C-atoms of their CH groups: the H-atoms of i-Pr(a) are more deshielded by 0.75-1.111 ppm and its C-atoms are more shielded by 10.0-160.0 ppm as compared to the corresponding atoms of i-Pr(b). i-Pr(a) is cis (on the N3-homocycle) to a large substituent (such as i-Pr, Me, CH2OH) and to a lone pair, while i-Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH3 and CH2OH groups at N(1) of 3 and 4 in the series b and c.
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    URL: http://dx.doi.org/10.1002/hlca.19870700216
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    Synthese eines Nickel(II)-B,C,D-hexadehydrocorrinats durch (A→D)-CyclisierungKurzmitteilung: [1].Professor Dr. Gerhard Quinkert zum 60. Geburtstag gewidmet (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 402-411 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Nickel(II) B,C,D-Hexadehydrocorrinate by (A→D)-Ring ClosureThe B,C,D-hexadehydrocorrin of type 10 fills a gap in the corrin family whose members can occur at different oxidation levels. We report here on the synthesis of a correspondingly protected secocorrin 23 and its convenient cyclization to 10
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    URL: http://dx.doi.org/10.1002/hlca.19870700219
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    Studies on the Biosynthesis of Tabtoxin (Wildfire Toxin). Origin of the Carbonyl C-Atom of the β-Lactam Moiety from the C1-Pool (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 412-422 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Re-isolation of Pseudomonas tabaci strain NCPPB 2730 from its host, the tobacco plant, led to an activation of the bacteria in order to produce the β-lactam dipeptide tabtoxin (Wildfire toxin, 1). Incorporation of several 14C-labelled amino acids as well as L-[methyl-13C]methionine, L-[1,2-13C2]- and L-[3,4-13C2]aspartate, rac -[1,2-13C2]glycerol, and [1,2-13C2]acetate into isotabtoxion (2) demonstrated that the building blocks of tabtoxin (1) are L-threonine, L-aspartate, the Me group of L-methionine and a C2-unit derived from the C3-pool (Fig. 3). The Me group of L-methionine provides the carbonyl C-atom of the β-lactam moiety. These findings represent a novel pathway in β-lactam biosynthesis. Mechanistic aspects with respect to the β-lactam ring formation are discussed. A biradical 16 is proposed as an intermediate during the cyclization of a N-formyl-α-amino ketone 15.
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    URL: http://dx.doi.org/10.1002/hlca.19870700220
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 488-491 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700229
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    On the Purported Structure of Cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 480-487 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the bis(sulfonium salt)7 in a solution of Na2CO3 in H2O/EtOH yielded three main products 8-10. The spectroscopic data of 8 were identical to those which led Mithcell and Sondheimer to assign them to cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (3). Our investigations show, however, that the correct structural assignment leads to the structure of 7,7a-dihydrodibenzo[de,mn]naphthacene (8).
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    URL: http://dx.doi.org/10.1002/hlca.19870700228
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    Masthead (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700101
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    Mehrstufige Redoxsysteme. XLIX. MitteilungXLVIII. Mitteilung:[1]. Mit π-Systemen substituierte 1,3-Dimethylidencyclobutane: Synthese und Eigenschaften (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 929-941 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multistep Redox Systems. 1,3-Dimethylidenecyclobutanes Substituted by π-Syntheses and PropertiesAs potential redox systems 1,3-dimethylidenecyclobutanes are synthesized in which the ‘exo’-methylidene group participates in a cyclopentadienyl (typeC4)or cycloheptatrienyl (type A5) system. Benzo-annellated systems are also described. The formation of the C=C bond by the reaction of thioketones (3 and 31) with diazo compounds is extended to extended to 1,6,7,21, and 24, which so far had not been employed. In some cases, intermediate thiiranes can be isolated (e.g.4) which are smoothly transformed into the target compounds of types C4 and A5 by extrusion of sulfur. The new C=C bonds may be introduced stepwise, thereby allowing the synthesis of unsymmetrically substituted 1,3-dimethylidenecyclobutanes (e.g. 20 and 35). Reduction of by Na does not produce bicyclobutanes but compounds 43 and 44 with one dihydrofulvene unit.
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    URL: http://dx.doi.org/10.1002/hlca.19870700404
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    Verecynarmin A, a Novel Briarane Diterpenoid Isolated from Both the Mediterranean Nudibranch Molluse Armina maculata and its Prey, the Pennatulacean Octocoral Veretillum cynomorium (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 984-991 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The briarane diterpenoid verecynarmin A (=(-)).(8R,9S,11R,12aR,4Z,6Z)-11,12-epoxy-8,8a,9,10,12,12a,13-octahydro-1,5,8a,12-tetramethylbenzo[4,5]cyclodeca[1,2-b]furan-9-yl acetate; ((-)-1) is shown to be contained in both the Mediterranean nudibranch mollusc Armina maculata(RAFINESQUE) and its prey, the pennatulacean octocoral Veretillum cynomorium(PALLAS). The structure is mainly solved by 1D-NMR, 2D-NMR, and NOE studies of (-)-1. However, the relative configurations at the epoxide and angular methyl centres, as well as the preferred conformation, are established by shift-reagent and NOE studies of diol(-)-4 obtained by epoxide-ring opening of (-)-1 with LiA1H4. The absolute configuration is established via deacetylation of (-)01 followed by Horeau's esterification.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700408
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  • 80
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    Oxidationsreaktionen methyl-substituierter 2,1,3-Benzothiadiazole und 2,1,3-Benzoselenadiazole mit Selen-dioxid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 997-1000 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation Reactions of Methyl Substituted 2,1,3-Benzothiadiazoles and 2,1,3-Benzoselenadiazoles with Selenium DioxideThe synthesis 5-8 by oxidation of 4-methyl-(1),5-methyl(2), 5,6-dimethyl-2,1,3-benzoselenadiazole (3), and 5,6-dimethyl-2,1,3-benzothiadiazole (4), respectively, with selenium dioxide as well as their spectroscopic properties are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700411
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  • 81
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    Steric Effects on Reaction Rates. Part IX. Force-Field Parameters for Bridgehead and Rigid Tertiary Carbenium Ions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1017-1024 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular-mechanics calculations for strain of carbenium ions are tested using Bentley's unified reactivity scale for bridgehead solvolysis as reference. Excellent correlations are obtained for solvolytic bridgehead reactivity with the calculated steric-energy difference (ΔEst) between substrate (R—H or R—OH) and cation (R+). After adjustment of appropriate force-field parameters, the approach is successfully extended to the rigid, but planar cations derived from structures 15-20; however, the general set of parameters cannot be applied to highly strained systems such as the cation formed from 17. With all of the 18 sets of parameters tested, the 2-endo-norbornyl derivative 16, is adequately correlated, while the exo isomer 15 exhibits enhanced reactivity by a factor of ca. 102 to 103.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700414
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  • 82
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    Complexes of 2,2′,2″-Nirtilotriphenol. Part IV. Cage Compounds with Phosphorus(III) and Phosphorus(V) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1063-1069 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,2′,2″-nitrilotriphenol reacts with P(III) and P(V) compounds to form corresponding phosphorus complexes. Syntheses and NMR data of 2,2′,2″-nitrilotriphenyl phosphite (II), 2,2′,2″-nitrilotriphenyl phosphate (III) and of a hydrolysis product of II, 2,2′-[N-(2-hydroxyphenyl)imino]diphenly phosphonate (IV), are reported, as well as crystal structures of II and IV. Phosphite II shows a bicycloundecane framework; no NċPinteraction is present. The phosphonate IV shows two coordinated and one dangling phenol group; the N-atom does not interact with the P-atom. Strong acids protonate II as well as III to form cations: in these, NMR evidence indicates coordination of the N-atom to the P-atom.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700418
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  • 83
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    Octacarbonyldicoblat-Inauced (1,3) H Shits in 1-Methylallenecarboxylates and Allenic LactonesDedicated to Professor Dr. André S. Dreiding (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1070-1075 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The allenecarboxylates 1a,b and allenic lactones 4a,b undergo thermally induced (1,3) H Shifts in the presence of Co2(CO)8. The non-isolated 1,3-dienes 2a,b react further affording the Diels-Alder Adducts 3a,b Scheme 1 in high yields. These adducts were not formed in the case of the 2-vinybutenolides 5a,b. On irradiationin the presence of Co2(CO)8 or Mn2(Co)10, the studied allenes reacted in a different manner, yielding either cyclization products 7 and 8 (Scheme 3) or products 9 and 10, formed via H abstracton and solvent addition (Schemes 4 and 5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700419
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  • 84
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    Brominations of Cyclic Acetals from α-Amino Acids and α- or β-Hydroxy Acids with N-Bromosucinimide (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1104-1114 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of novel electrophilic building blocks for the synthesis of enantiomerically pure compounds (EPC) is described. Thus, the 2-(tert-butyl)dioxolanones, -oxazolidinones, -imidazolidinones, and -dioxanones obtained by acetalization of pivalaldehyde with 2-hydroxy-, 3-hydroxy-, or 2-amino-carboxylic acids are treated with N-bromosuccinimide under typical radical-chain reaction conditions (azoisobuytyronitril/CCl4/reflux). Products of bromination in the α-position of the carbonyl group of the five-membered-ring acetals are isolated or identified (2, 5, and 8; Scheme 1). The dioxanones are converted to 2H, 4H-dioxinones under these conditions (12, 14, 15, 21, and 22; Schemes 2 and 3). The products can be converted to chiral derivatives of pyruvic acid (methylidene derivatives 3 and 6) or of 3-oxo-butanoic and -pentanoic acid (16 and 23). The mechanism of the brominations is interpreted. The conversion of serine to enactiomcrically pure dioxanones 26-28 (Scheme 4) is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700423
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  • 85
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    Addendum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1229-1229 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700428
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  • 86
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1230-1231 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700429
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  • 87
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    Enzyme-Catalyzed Hydrolysis of Some Functionalized Dimethyl MalonatesPresented at the meeting of the Swiss Chemical Society, Berne, October 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1250-1254 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the preparation of (+)-(R)-methyl hydrogen 2-(tert-butoxymethyl)-2-methyl-malonate (5e) in synthetically useful amounts from readily available starting material.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700503
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  • 88
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    Diels-Alder-Reaktionen von 2,4-Bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien mit HeterodienophilenTeil der geplanten Dissertation von U. R. [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1255-1260 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diels-Alder Reactions of 2,4-Bis{[(tert-Butyl)dimethylsilyl]oxy}-3-aza--1,3-pentadien with HeterodienophilesThe 2,4-bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien(2) reacts via the Diels-Alder adducts 3, 6a-c, and 8a, b, which cannot be isolated, giving the triazines 4, 7a-c, and the oxadiazines 9a, b. The hydrolysis of 4 in MeOH affords the N-acetyl-acetamid derivative 5. The formula of 9a is proven by an X-ray-structure analysis.
    Notes: No. Abstract.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700504
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  • 89
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    Zwei weitere Iridoid-glycoside und ein Monoterpen-glycosid aus Sambucus ebulus L. (Caprifloiaceae). 3. Mitteilung über die Inhaltsstoffe der Zwergholunderwurzel (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 91-101 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Iridoid Glycosides and a Monoterpene Glycoside from Sambucus ebulus L. (Caprifloiaceae)From the roots of Sambucus ebulus L., two novel valeriana-type ester iridoid glycosides, 6′-O-apiosylebuloside (1) and 7,7-O-dihydroebuloside (3), along with the open-chain monoterpene glycoside 5 were isolated. Their structure elucidation is based mainly on one- and two-dimensional NMR methods. 1H,1H-COSY experiments permitted complete assignment of signals arising from the disaccharide unit in 1. Biogenetically, 3 seems to represent the equivalent of loganin in the valeriana-type series of iridoid glycosides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700111
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  • 90
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    Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 116-120 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ‘D-Isothreonine’ and ‘L-Alloisothreonine’ Starting from L-AlanineStarting from L-alanine, ‘D-isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L-alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700113
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  • 91
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    Oxidative Breaking of Long-Chain Acetylenic Enol Ethers of Glycerol of the Marine Sponges Raspailia pumila and of Model Compounds with Aerial Oxygen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1400-1411 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The raspailynes (novel long-chain enol ethers of glycerol having the enol ethers double bond conjugated in sequence, to an acetylenic and an olefinic bond, isolated from the North-East-Atlantic sponges Raspailia pumila and R. ramosa) are stable under normal hydrolytic conditions for enol ethers. In contrast, when their solutions are evaporated, these lipids such as raspailyne Bl (=(-))-3-[(1Z,5Z)-(tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(--2) rapidly react with aerial O2 under normal laboratory-daylight conditions, with rupture of the C=C enol ether bond to give 1-O-formylglycerol (3) and an aldehyde (such as tridec-4-en-2ynal(4) from (-)-2). This reaction must be caused by triplet O2, since thermally generated singlet O2 has no effect on (-)-2 in solution. That the mere presence of an enol-ether moiety conjugated to an acetylenic group is responsible for such a behaviour is demonstrated with the model compounds 1-methoxypentadec-1-en-3-yn-5-ol (6a) and its 5-O-acetyl or 5-O-tetra-hydropyranyl derivatives 6b and 6c, respectively. Resistance to both hydroytic conditions and singlet O2 of these compounds is thought to arise from electron depletion at the enol-ether C(beta;) atom by the acetylenic group. Plausible reaction pathways for enol-ether bond rupture in these compounds by aerial O2 are outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700521
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  • 92
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    Catalytic Intramolecular Palladium-Ene Reactions. Preliminay CommunicationPresented at the ‘4th IUPAC-Symposium on Organometallic Chemistry Directed towards Organic Synthesis’ (OMCOS IV), July 28, 1987, Vancouver, Canada. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1477-1481 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism (D → E → F, Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β-H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd (13 → 14 → 15).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700604
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  • 93
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    Drug-induced modifications of the immune response part 9Part8: [1]4-(Arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenylcycolopropyl)furan-3-carboxamides as Novel Antiallergic Compounds (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1526-1530 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and antiallergic activity of a series of 4-(arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenyl-cyclopropyl)furan-3-carboxamides 10 are described. Treatment of N-substituted 2-amino-4,5-dihydro-4-oxofuran-3-carboxylic acids 9 with chlorooxobis(2-oxo-1,3-oxazolidin-3-yl)phosphorus (2) and an appropriate aromatic amine in the presence of Et3N, resulted in a novel 3(2H)-furanone-→2(5H)-furanone rearrangement that led to the facile preparation of the new amides 10. The latter exerted a potent antiallergic activity when tested in the dermal vascular permeability and active anaphylaxis assays in rats. The most active compound 10b inhibited the action of serotonin, histamine, and bradykinin by 94, 92, and 100%, respectively, when administered intraperitoneally to rats at doses of 100 mg/kg. The present series of 10 represents a novel class of antiallergic agents.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700609
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  • 94
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    Notiz über die Verwendung von 3-(Arylsulfonyl)-2-cycloalkenonen als 2-Cycloalkinon-Synthese-Equivalente (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1537-1539 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Use of 3-(Arylsulfonyl)-2-cycloalkenones as Synthesis Equivalents of 2-Cycloalkynones3-(Arylsulfonyl)-2-cyclopentenones and 3-phenylsulfonyl-2-cyclohexnone undergo Diels-Alder reactions with cyclopentadiene. Elimination of arylsulfinic acid leads to products, which would have been obtained directly from a Diels-Alder reaction of 2-cyclopentynone or 2-cyclohexynone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700611
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  • 95
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    Inhibition of Electron-Hole Recombination in Substitutionally Doped Colloidal Semiconductor Crystallites (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1596-1604 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The subtitutional doping of 120-Å- sized TiO2 Particles with Fe(III)ions has a profound effect on the charge carrier recombination time in this colloidal semiconductor. In undoped particles, the mean lifetime of an electronhole pair is ca. 30 ± 15 ns. Doping with 0.5% Fe(III) drastically augments the charge-carrier lifetime which is extended to minutes or hours. The slow character of the recombination dynamics in Fe(III)-doped colloids was confirmed by laser photolysis using the characteristic optical of electrons in TiO2 to monitor the time course of the reaction. EPR studies showed the Fe(III) ions to enter the host lattice on Ti(IV) sites, charge compensation taking place through the formation of oxygen vacancies. Valence-band holes produced under band-gap excitation react with these centers it the bulk forming Fe(IV), the conduction band electrons being trapped by Ti(IV) at the particle surface. Presumably, the spatial separation of the trapped electron and hole sites inhibits their recombination.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700617
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  • 96
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    The Radical Anions of 1,2-diphenylcyclohexene and Structurally Related Compounds. Conformational ESR and ENDOR studies (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1558-1568 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR, ENDOR, and TRIPLE resonance studies have been performed on the radical anions of 1,2-diphenylcyclohex-1-ene (4), 1,2-di(perdeuteriophenyl)cyclohex-1-ene ((D10)4) the trans-configurated 3,4-diphenyl-8-oxabicyclo[4.3.0]non-3-ene (5) and its 2,2,5,5-tetradeuterio derivative (D4)5, and 2,3-diphenyl-8,9,10-trinorborn-2-ene (6). The spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} exhibit strong temperature dependence along with a specific broadening of ESR hyperfine lines and proton ENDOR signals. The coupling constant, which bears the main responsibility for these features, is that of the β-protons in the quasi-equatorial positions of the cyclohexene ring, and the experimental findings are readily rationlized in terms of relatively modest conformational changes without invoking the inversion of the half-chair form. The hyperfine data for the β-protons in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} closely resemble the corresponding low-temperature values for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document}, However, the ‘unusual’ features observed for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} are absent in the ESR and ENDOR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document}, because the half-chair conformation of the cyclohexene ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} is deprived of its flexibility. Although the boat form of this ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} is also rigid, the spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} are temperature-dependent, due to an interconversion between two propeller-like conformations of the phenyl groups. The pertinent barrier is 30 ± 5 kJ·mol-1. An analogous interconversion presumably takes place in \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} as well, but, unlike \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document}, it is not amenable to experimental study.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700614
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  • 97
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    Synthesis and Formation of Ironcarbonyl Complexes of 3′,3′-Dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane]. Single-Crystal and Molecular Structure of syn,exo2,3-anti,endo5,6-trans-μ-[(1r,2r,3s,4s,5s,6r)-c,2,3,c-η:c,5,6,c-η-(3′,3′-dimethyl-2,3,5,6,-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane])]bis(tricarbonyliron)Interaction between non-conjugated chromophores, Part 27. Part 26, see [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1638-1648 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3′,3′-dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane] (3) was derived from 6,6-dimethylfulvene and maleic anhydride. Its reaction with 1 equiv. of ethylenetetracarbonitrile (TCNE) was not regioselective and gave a 1:1 mixture of the corresponding monoadducts 10 and 11. The rate constants of the Diels-Alder additions of 10 and 11 to TCNE were significantly smaller than that of the reaction 3 + TCNE. Monocomplexation of 3 with Fe2(CO)9 was highly exo-face selective giving a mixture of the corresponding monocomplexes 12(anti-exo) and 13(syn-exo). The latter were complexed with Fe2(CO)9 in a non-stereoselective fashion, giving mixtures of the dicomplexes 14(anti-exo, syn-endo), 15(anti-exo,syn-exo), and 16(anti-endo, syn-exo). Exchange of the CO ligands was a faster process for the endo-Fe(CO)3 moieties than for the exo-Fe(CO)3 moieties. Line-shape analysis of the 13C-NMR spectrum of 15 established that one of the exo-Fe(CO)3 groups in 15 rotates ca. 3 times as fast as the other Fe(CO)3 group at 40°. The structure of the anti-endo, syn-exo dicomplex 16 was determined by single-crystal X-ray diffraction studies.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700621
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    New Antifungal Chromenyl Ketones and their Pentacyclic Dimers from Hypericum revolutum VAHLPresented in part at the 34th Annual Congress on Medicinal Plant Research, Hamburg, FRG, 22-27 September, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1694-1702 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new 2H-1-benzopyranyl ketones 1 and 2 and three new pyrano[3,2-c: 4,5,6-d′ e′]di[1]benzopyrandiyl diketones 3, 4a/4b, and 5 have been isolated from the leaves and twigs of Hypericum revolutum VAHL (Guttiferae). The structure of 3 (hyperevoline) was established by X-ray analysis as 1,1′-[1,13,13a,13b-tetrahydro-5,8,10-trihydroxy-2,2,6,9,13,13-hexamethyl-2H, 7aH-pyrano[3,2-c:4,5,6-d′e′]di[1]benzopyran-4, 11-diyl]bis[2-methyl-1-propanone]. The structures of the isolated compounds were established by spectroscopic (UV, IR, EI-MS, 1H- and 13C-NMR) and chemical (acetylation and acidic dimerization) methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700705
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  • 99
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    Mammalian Alkaloids: Configurations of Optically Active Salsoline- and 3′,4′-Dideoxynorlaudanosoline-1-carboxylic AcidsSalsoline and norlaudanosoline are well known alkaloids, and these names will be used in the General Part (for systematic names, see Expert. Part). The systematic name for salsoline is 1-methyl-7-methoxy-1,2,3,4-tetrahydroisoquinolin-6-ol and that for norlaudanosoline, also named tetrahydropapaveroline, is 1-(3′,4′-dihydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1721-1731 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the optical isomers of (±)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate ((±)-2) was accomplished by reaction of (±)-2 with (+)-(R)-1-phenylethyl isocyanate, separation of the urea diastereoisomers (-)-4A and (+)-4B, and alcoholysis of the ureas in refluxing BuOH. Optically active isoquinoline-carboxylates 2A,B and hydantoins 8A,B isolated were characterized. The absolute configuration of the reaction products was established by X-ray analysis of the optically active hydantoin (+)-8A. Hydrolysis of the methyl isoquinolinecarboxylates 2A,B with 48% HBr soln. at reflux afforded the desired optically active 3′,4′-dideoxynorlaudanosoline-1-carboxylic acids 1A,B required for enzyme-inhibition studies. Details of the X-ray diffraction analysis of (+)-methyl salsoline-1-carboxylate hydrobromide ((+)-11A·HBr) prepared earlier are included. CD spectra of (+)-(S)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate hydrobromide ((+)-2A. HBr) and (-)-(R)-methyl salsoline-1-carboxylate hydrochloride ((-)-11B·HCl) confirmed the assignment of their (S)- and (R)-configurations, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700707
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  • 100
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    Determination of the Quantum Yield of Intersystem Crossing of Rose Bengal (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1760-1773 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (ϕet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · ϕet = Φ(1O2), with ϕet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700712
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