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  • 1995-1999
  • 1985-1989  (2,514)
  • 1925-1929
  • 1989  (2,514)
  • General Chemistry  (1,242)
  • Inorganic Chemistry  (665)
  • Engineering  (566)
  • Magnetic resonance imaging
  • Nuclear reactions
  • Numerical Methods and Modeling
Material
Years
  • 1995-1999
  • 1985-1989  (2,514)
  • 1925-1929
Year
Keywords
  • 1
    ISSN: 1432-1440
    Keywords: Periarteritis nodosa ; Magnetic resonance imaging ; Cerebral lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The course is reported of a patient with periarteritis nodosa who initially presented with neurological symptoms. Multiple cerebral lesions were documented by the first magnetic resonance imaging (MRI) investigation. The majority of these had disappeared completely in the follow-up MRI studies. In contrast to neurological improvement the patient eventually died due to multiorgan failure. Postmortem histological examination revealed no pathological findings in the brain except one single necrotic area already known from MRI. Remissions of histological and angiographic alterations in periarteritis nodosa have been described as “local healing” leading to fibrosis and scarring. Our findings suggest that restitutio ad integrum may occur, at least in cerebral lesions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Surgical and radiologic anatomy 11 (1989), S. 155-161 
    ISSN: 1279-8517
    Keywords: Brain stem ; Magnetic resonance imaging ; Anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé A partir d'une exploration IRM de la fosse postérieure de 30 sujets volontaires sains une corrélation anatomoradiologique a été effectuée. L'examen fut pratiqué sur un appareil CGR Magniscan de 0,5 Tesla avec une séquence d'inversion récupération (TI: 21 ms, Tr. 2 000 ms, Ti: 500 ms). Cette séquence nous paraît être celle qui visualise le mieux la substance grise, la substance blanche et le liquide cérébrospinal. Afin d'étudier la configuration des principales structures du tronc cérébral 8 plans de coupes horizontales et 3 sagittales sont proposés.
    Notes: Summary Magnetic resonance imaging of 30 normal volunteers' posterior fossae was performed on a CGR Magniscan machine with a magnetic field strength of 0,5 Tesla. We chose the inversion recovery signal with a Tr of 2,000 ms, a TE of 21 ms and an inverse time of 500 ms. This sequence gives a better definition of the grey matter, the white matter and the CSF. To study the brain stem we suggest 8 horizontal and 3 sagittal sections.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 14 (1989), S. 308-310 
    ISSN: 1432-0509
    Keywords: Hemangioma, spleen ; Thrombocytopenia ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In contrast to the only previously published description, the magnetic resonance appearance of a splenic hemangioma was markedly heterogeneous on T2-weighted images due to extensive infarction and large vascular pools. Magnetic resonance images correlated precisely with the pathological findings. The hemangioma caused thrombocytopenia, a well-documented albeit rare hematologic phenomenon associated with visceral hemangioma.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 129-133 
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Computed tomography ; Brain stem tumour ; Brain stem haemorrhage ; Brain stem infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ninety-six magnetic resonance imaging (MRI) studies demonstrating solitary brain stem lesions were reviewed in order to establish distinguishing features between tumours and other lesions. Histological confirmation of the radiological diagnoses was obtained in 33% of patients. The morphology of the lesion rather than its signal characteristics was the most useful feature in differential diagnosis, except after haemorrhage. However, areas of abnormal T2 recovery time were significantly more extensive than areas of abnormal T1 recovery time in tumours at presentation. In other lesions and in tumours following radiotherapy induced regression, the extent of abnormal T1 and T2 signal was the same. Possible reasons for this observation are discussed. The accuracy of computed tomography (CT) and MRI were similar for lesions causing brain stem expansion but for small lesions MRI was more sensitive and provided better topographical information.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Cerebral angiography ; Atrial myxoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of left atrial myxoma presenting exclusively with neurological symptoms, studied with magnetic resonance imaging (MRI) combined with cerebral angiography and computed tomography (CT) is reported. Typical angiographic findings suggested the diagnosis of myxoma. MRI showed multiple ischemic lesions disseminated throughout the entire brain, some of which had been clinically asymptomatic. Because of its sensitivity in identifying small cerebral infarcts, MRI should prove in the future to be a first-choice technique in the evaluation of the presence of and extent of cerebral involvement in embolic left atrial myxoma.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 213-216 
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Spine ; 3DFT ; Gradient echo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A prospective study of 16 patients was performed to compare quantitatively a contiguous single slice 2DFT version with a 3DFT version of a short TR, variable flip angle, gradient echo (GRASS) pulse sequence. The 3DFT GRASS scans had higher signal-to-noise ratios (SNR) of cord and CSF compared to the single slice 2DFT GRASS scans. The 3DFT GRASS scans, however, had lower CSF-cord and CSF-disc contrast than the single slice 2DFT version. The 3DFT GRASS sequence demonstrated comparable contrast only on the end slices of an imaging volume suggesting influence of an entry phenomenon. The lower CSF-cord and CSF-disc contrast of the 3DFT GRASS technique diminished its usefulness in the diagnosis of cervical disc disease compared to the single slice 2DFT GRASS technique. Two different slice thicknesses (3 mm and 5 mm) were investigated with the 2DFT GRASS technique and found to be comparable although the 3 mm scans had sharper disc and dural margins because of less partial volume artifact.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 382-385 
    ISSN: 1432-1920
    Keywords: Cervical spine ; Disk herniation ; Myelography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eleven operated herniated disks in 10 patients were evaluated preoperatively with plain films, myelography and magnetic resonance imaging. Plain X-ray was a valuable supplement to MRI for studying the bony changes. Myelography showed 7 of 11 herniated disks while MRI gave correct diagnosis in all. It is concluded that MRI can replace myelography and computerized tomography in the preoperative evaluation of cervical herniated disk. The other examinations may be supplementary in some cases.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 430-432 
    ISSN: 1432-1920
    Keywords: Amnesia ; Glioblastoma ; Hippocampal formation ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report a unique case of glioblastoma which caused permanent amnesia. Magnetic resonance imaging showed the lesion to be limited to the hippocampal formation bilaterally. Although glioblastoma extends frequently into fiber pathways and expands into the opposite cerebral hemisphere, making a “butterfly” lesion, it is unusual for it to invade the limbic system selectively to this extent.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1920
    Keywords: Thoracic disc herniation ; Spine, intervertebral discs ; Spine, MR studies ; Spinal cord, compression ; Contrast media ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 276-277 
    ISSN: 1432-1920
    Keywords: Cockayne syndrome ; White matter ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary MRI findings are reported from two patients with Cockayne syndrome (CS) type I, aged 11 and 37 years. Changes were compatible with diffuse white matter hypomyelination. Basal ganglia calcification was present in both, marked cerebellar atrophy in the older patient. MRI may support the diagnosis of CS in the appropriate clinical context. The view that CS is a dysmyelinating disorder is further substantiated.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 177-179 
    ISSN: 1432-1920
    Keywords: Malignant fibrous histiocytoma ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rare case of primary MFH of the brain is described together with the CT and MRI findings. The radiological appearance of this tumor is discussed in conjunction with the material published in other case reports.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 293-298 
    ISSN: 1432-1920
    Keywords: Pituitary microadenoma ; Magnetic resonance imaging ; Gadolinium DTPA ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ten patients with biochemical evidence of a hormonally active pituitary adenoma were examined by dynamic contrast enhanced computed tomography (CT) and then by pre and post Gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging (MRI). Excluding one false positive case, CT and unenhanced MRI were comparable in the detection of microadenoma. Post Gd-DTPA examination gave more clear evidence of the actual adenoma in two patients and aided in the demonstration of a third. However, in two others all imaging techniques failed to demonstrate the microadenoma subsequently found at surgery. On the post enhancement MRI it was easier to assess the relationship of a tumour to the cavernous sinus and to visualise the relationships of the parasellar carotid arteries.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 403-407 
    ISSN: 1432-1920
    Keywords: Vertebral artery ; Basilar artery ; Arterial occlusion ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Magnetic resonance (MR) images of nine patients with intracranial vertebral artery occlusion (five proved, four presumed) have been reviewed. In two of nine, both vertebral arteries were occluded and in five of the nine, the basilar artery was also blocked. All occluded arteries showed absence of flow void and were clearly demonstrated as mildly hypo-∼mildly hyperintense structures to brainstem parenchyma on the T1-weighted images. In two of five patients with basilar artery occlusion, retrograde filling of the distal basilar artery was detected. Thus, MR imaging, in particular the T1-weighted image, is a pertinent diagnostic modality for evaluating intracranial vertebral artery occlusion. Angiography does not seem to be required for confirmation.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 190-192 
    ISSN: 1432-1920
    Keywords: Epidural lipomatosis ; Lumbar myelography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Epidural lipomatosis may be unassociated with steroid use and should be considered in the differential diagnosis of lumbar radiculopathy. This may cause widening of the spinal canal on plain film and complete block on myelography. CT or MRI is diagnostic.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 98-101 
    ISSN: 1432-1920
    Keywords: Brain cysts ; Anomalies, congenital ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cases of large asymptomatic cysts of the lateral ventricle are presented. The cyst walls or cyst contours were demonstrated well by proton density-weighted or T2-weighted spin echo images. These cysts are being detected as incidental findings in increasing frequency with the increasing use of MR imaging. Our data and review of the literature suggest that surgical intervention is not necessarily warranted, but that careful clinical evaluation is indicated. The diagnostic problem of intraventricular cysts is also discussed.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 31 (1989), S. 258-262 
    ISSN: 1432-1920
    Keywords: Neuro-Behçet's syndrome ; Behçet's syndrome ; Brain stem type neuro-Behçet's syndrome ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain stem type neuro-Behçet's syndrome was studied with enhanced CT and MRI during the acute and chronic stage of the illness. During the acute stage, brain CT revealed a low density lesion in the brain stem extending from the lower pons up to the midbrain ventrolaterally with marginal enhancement effect. T2-weighted image showed a high signal intensity lesion in the brain stem which mainly involved the basis ponti, tegmentum, tectum and cerebral peduncle. During the chronic stage, the lesion became low in signal intensity with T2-weighted image and reduced in its size without enhancement in brain CT. The prolonged relaxation time of the lesions was gradually normalized with steroid treatment. Sequential brain CT with enhancement and MRI study with T1- and T2-weighted images were useful to detect the lesions and to evaluate the activity in the neuro-Behçet's syndrome.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1432-1920
    Keywords: Brain ; Magnetic resonance imaging ; Cavernous angioma ; Arteriovenous malformation ; (AVM) ; Venous angioma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twelve patients with cerebral vascular malformations (5 cavernous angiomas, 1 thrombosed arteriovenous malformation, and 6 venous angiomas) were studied with magnetic resonance (MR) imaging. All lesions were clearly depicted. Characteristic MR findings were obtained mainly on T2-weighted images: a markedly low intensity area was always seen. The margins of arteriovenous malformation (AVM) and venous angioma were irregular while those of cavernous angioma were smooth in all planes on T2-weighted images. Gradient-echo (GrE) pulse sequences were more sensitive than T2-weighted spin echo (SE) in lesion detection. MR imaging could play an important role in the differential diagnosis of cerebral vascular malformations.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 18 (1989), S. 253-259 
    ISSN: 1432-2161
    Keywords: Fibrous metaphyseal defect ; Magnetic resonance imaging ; Determination of origin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sixteen patients with fibrous metaphyseal defects were examined with both plain radiography and magnetic resonance (MR) imaging. Depending on the age of the fibrous metaphyseal defects, characteristic radiomorphologic changes were found which correlated well with MR images. Following intravenous Gadolinium-DTPA injection, fibrous metaphyseal defects invariably exhibited a hyperintense border and signal enhancement. Healed lesions exhibited a transition to normal bone marrow. A line through the maximum longitudinal diameter of a fibrous metaphyseal defect invariably led to a point of tendinous or ligamentous insertion. Coronal MR images demonstrated the maximum longitudinal extension and the respective inserting tendon or ligamentous structure at the epiphyseal line.
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  • 19
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Pulse sequences ; Primary bone tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A prospective magnetic resonance imaging (MRI) study was carried out in 13 patients (19 examinations) with primary bone tumours to assess the relative value of each of four pulse sequences in showing the extent and nature of the lesion. The four pulse sequences used were a T1-weighted spin-echo (SE544/44), a T2-weighted spin echo (SE1500/80), a short TI inversion recovery (STIR) (IR500/100/44), and a partial saturation (PS) (PS500/22) with field echo data collection. For soft tissue disease the combination of PS and STIR gave better definition of the boundary of the tumour than the more conventional T1 and T2-weighted spin echo sequences. For the demonstration of bone cortex, periosteal change and calcification, T1 and T2-weighted spin echo sequences were better. However, for calcified tissues, plain radiographs were better than either MRI combination. On the assumption that plain films will be available in all cases, PS and STIR sequences could therefore be substituted for T1 and T2-weighted spin echo sequences allowing an increase in soft tissue detectability for lesions in both red and yellow marrow.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 18 (1989), S. 523-526 
    ISSN: 1432-2161
    Keywords: Spine ; Scheuermann disease ; Magnetic resonance imaging ; Disc degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Comparison of the radiographic signs of Scheuermann disease and the corresponding disc degeneration on thoracolumbar magnetic resonance (MR) images was made in 21 young patients. Marginal sclerosis, Schmorl nodes and narrowed disc spaces, but not irregular or wedge-shaped end-plates, were significantly associated with disc degeneration. Fifty-five percent of the discs in the patients with Scheuermann disease were abnormal on MRI, compared with 10% in asymptomatic controls. Our study confirms that thoracolumbar disc degeneration is enhanced in 20-year-old patients with low back pain who have radiological evidence of Scheuermann disease.
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  • 21
    ISSN: 1432-2161
    Keywords: Disc ; Disc disease ; Disc extrusion ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance (MR) imaging is useful in evaluating a variety of spinal pathologies including intervertebral disc disease. Herniated discs are commonly believed to undergo premature degeneration and produce low intensity signal on T2-weighted images. We reviewed 154 patients who were studied for disc herniations or other pathology. Fifty-nine (38%) had disc herniations and 7 of these (5%) had a fragment that was hyperintense with respect to the adjacent intervertebral disc on T2-weighted images. It is hypothesized that some disc fragments may contain a higher water content that causes prolongation of the T2 signal. The bright signal which is therefore seen on long TR long TE (T2-weighted) images may be a useful sign suggesting herniation or extrusion.
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 18 (1989), S. 585-590 
    ISSN: 1432-2161
    Keywords: Soft tissue tumors ; Bone tumors ; Magnetic resonance imaging ; Low field strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Extremely low field magnetic resonance imaging (MRI) was evaluated in 16 patients with bone and soft tissue tumors, both benign and malignant. Twelve of the lesions were located in the lower extremity, 2 in the gluteal and 2 in the shoulder region. The findings were compared to the results of computed tomography (CT). Low signal-to-noise ratio and poor spatial resolution result in an image quality which is inferior to that obtained with MR imaging at higher field strengths. In spite of this, the diagnostic information seems to be at least comparable to that obtained from CT.
    Type of Medium: Electronic Resource
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  • 23
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Gadolinium-DTPA ; Rheumatoid arthritis ; Dynamic magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-four joints (19 knees, 15 wrists) of 31 patients suffering from rheumatoid arthritis and related disorders were examined prior to and following intravenous administration of Gadolinium-DTPA (0.1 mmol/kg body weight). T1-weighted spin-echo sequences and the gradient-echo technique FLASH were applied. FLASH scanning was used for the registration of the time-dependent changes of signal intensity following Gd-DTPA. Synovial proliferations exhibited a rapid and marked increase of signal intensity whereas fatty tissue, bone marrow, muscle and synovial effusion demonstrated only minor changes, causing enhanced contrast between synovial pannus and joint effusion or other neighbouring structures. Within the synovial pannus, ratios (absolute signal increase) of 131.3±53.4% and 122.9±51.1% were found in T1-weighted spin-echo and in FLASH sequences respectively. The average signal increase gradient of pannus (108.2±70.6%/min) was significantly (p〈0.001) different from muscle (13.4±7.8%/min), fatty tissue (10.2±8.4%/min), bone marrow (5.5±7.1%/min), and joint effusion (14.7±7.8%/min).
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 149 (1989), S. 162-163 
    ISSN: 1432-1076
    Keywords: Antithrombin III ; l-Asparaginase ; Magnetic resonance imaging ; Osteonecrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a child with acute lymphocytic leukaemia who developed simultaneous osteonecrosis of vertebrae and cerebral thrombosis duringl-asparaginase therapy. Fibrinogen, antithrombin III and plasminogen were decreased. Fresh frozen plasma in addition to antithrombin III concentrates were used to replenish these haemostatic proteins.l-asparaginase induced coagulopathy may cause osteonecrosis.
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 236 (1989), S. 177-181 
    ISSN: 1432-1459
    Keywords: Cheiro-oral syndrome ; Magnetic resonance imaging ; Computed tomography ; Central gyrus ; Thalamus-Brain stem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four cases of the cheiro-oral syndrome are reported, with a review of the clinical symptoms and signs and the neuroradiological methods used to demonstrate the responsible lesion. In each case, angiography, computed tomography (CT) and magnetic resonance imaging (MRI) were performed. The lesion was found in the thalamus in three cases and in the pons in one. Infarction had occurred in three cases and haemorrhage in one. Angiography revealed normal findings in all cases. CT at the onset of the symptoms demonstrated a small haemorrhage in the thalamus in one case but was not helpful in the others, and MRI was required to identify infarction. The anatomical sites responsible for the cheirooral syndrome have been reported to be in the central gyrus, in the thalamus, and in the brain stem. The clinical symptoms and signs reported in the literature and in our four cases are reviewed to evaluate aetiological factors and clinical features according to the three different sites of lesions causing this syndrome.
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  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 236 (1989), S. 255-259 
    ISSN: 1432-1459
    Keywords: Japanese B encephalitis ; X-ray computed tomography ; Magnetic resonance imaging ; Geriatrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurological, computed tomography (CT) and magnetic resonance imaging (MRI) findings were recorded from 13 patients with Japanese encephalitis (JE) in the Kurume region diagnosed by serological criteria. The patients averaged 63 years of age, and 5 were older than 70 years. The serological data mostly indicated a primary response. Hemiplegia and tetraplegia were common, together with extrapyramidal signs. A few cases had a stroke-like onset and cerebral haemorrhage during the course of JE. CT and MRI in 7 cases revealed abnormalities in the thalamus and basal ganglia including the putamen. The CT and MRI findings from the acute stage to the convalescent stage were considered to be characteristic of JE.
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  • 27
    ISSN: 1432-1459
    Keywords: Sinus thrombosis ; Computed tomography ; Magnetic resonance imaging ; Thalamus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The case is reported of a patient with primary thrombosis of the internal cerebral veins who presented initially with unilateral and later developed bilateral thalamic lesions revealed by computed tomography. Magnetic resonance imaging and angiography confirmed the diagnosis. Upon anti-coagulation the patient recovered nearly completely.
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  • 28
    ISSN: 1432-1459
    Keywords: Multiple sclerosis ; Diagnosis ; Electrophysiological tests ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sixty multiple sclerosis (MS) patients (33 definite, 13 probale and 14 suspected were investigated by computed tomography (CT), magnetic resonance imaging (MRI), multimodality evoked potentials (EPs) and cerebrospinal fluid (CSF) electrophoresis. MRI abnormalities were found in 50 cases, while at least one abnormal evoked potential was detected in each of 52 cases. Brain-stem auditory evoked potentials were more sensitive than MRI for the detection of brainstem involvement. All the patients with oligoclonal bands had abnormal MRI and none of the patients with normal MRI had oligoclonal bands in the CSF. The number and the extent of MRI lesions were significantly correlated with the duration of disease and with the degree of disability. Our observations stress the importance of the combined use of MRI and EPs in detecting silent CNS lesions in MS patients.
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  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 236 (1989), S. 115-116 
    ISSN: 1432-1459
    Keywords: Palatal myoclonus ; Inferior olive ; Magnetic resonance imaging ; Pseudohypertrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four patients with palatal myoclonus (PM) were studied with magnetic resonance imaging (MRI). Increased signal intensity and bilateral enlargement of the inferior olives were recognized in two patients with bilateral PM, pontine haemorrhage and neuro-Behçet disease, and a similar olivary change on the contralateral side was noted in a case of pontine infarction with unilateral PM. These findings were consistent with the pathology. The changes were more obvious in proton density-weighted images than in T2-weighted images, which thus differ from the changes in common gliosis. The other patient with the syndrome of PM and progressive ataxia did not show any olivary change. These changes on MRI are considered to indicate pseudo-hypertrophy of the inferior olives, although this is not consistently shown by the imaging method.
    Type of Medium: Electronic Resource
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  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 236 (1989), S. 117-119 
    ISSN: 1432-1459
    Keywords: Cavernous angioma ; Optic tract ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A cavernous angioma of the right optic tract in a 35-year-old man is presented. The patient suffered from headaches and had a left homonymous visual field defect after subarachnoid haemorrhage and an intracerebral haematoma in the right temporomedial region, revealed by computed tomography (CT). Follow-up CT showed a small contrast-enhanced lesion in the right suprasellar and parasellar cistern. Angiography on three occasions did not reveal a vascular lesion. Magnetic resonance imaging was helpful both for diagnosis and planning surgical therapy. It showed typical signs of a cavernous angioma of the right optic tract; the diagnosis was confirmed by surgery and histological examination. This appears to be the first reported case of a cavernous angioma of the optic tract.
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  • 31
    ISSN: 1432-1459
    Keywords: Chronic inflammatory demyelinating polyneuropathy ; Cranial nerve lesions ; Magnetic resonance imaging ; Nerve biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five cases of chronic inflammatory demyelinating polyneuropathy are described in which cranial nerve involvement accompanied a more generalized neuropathy. Clinical, electrophysiological, radiological and nerve biopsy findings are presented. Cranial nerve lesions in this form of polyneuropathy may be related to lesions of the peripheral nerves or of the central nervous system, when they may be accompanied by MRI evidence of more widespread CNS demyelinating lesions. In cases of early onset, the occurrence of focal cranial nerve lesions may serve to distinguish chronic inflammatory from inherited demyelinating polyneuropathies.
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  • 32
    ISSN: 1432-1459
    Keywords: Carbon monoxide poisoning ; Midbrain syndrome ; Visual evoked potentials ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five patients (aged 19–52 years) were treated for a midbrain syndrome due to acute carbon monoxide poisoning and had clinical follow-up investigations for up to 18 months. Three patients recovered with minor neurological and neuropsychological deficits and resumed their premorbid life-style. One patient had normal findings, while the fifth remained in a permanent vegetative state. Initial CT of the brain may fail to detect low-density lesions in the globus pallidus. If present, these lesions may either have disappeared, diminished, or remained unchanged at follow-up. Long-term outcome seems to show a closer link to white matter changes, which are at present best investigated by magnetic resonance imaging. The additional value of determining visual evoked responses at repeated follow-up is suggested by the present investigation.
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  • 33
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    Child's nervous system 5 (1989), S. 172-176 
    ISSN: 1433-0350
    Keywords: Pineal cyst ; Pineal tumor ; Pineal lesion ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-two cases of pineal cyst diagnosed by magnetic resonance imaging (MRI) were reviewed and are described. The pineal cyst was demonstrated to be an area with slightly less intensity than the surrounding tissue and with slightly greater intensity than the CSF on T1-weighted images. On the T2-weighted images this lesion was identified as a high-intensity area with smooth margins and was homogeneous in nature. In three cases presenting with headache, compression of the vein of Galen was identified, and compression of the quadrigeminal plate was demonstrated in five cases. No patients presented with both pineal and quadrigeminal lesions. Of the cases, 63% were not detected by CT scanning alone. There were two cases in which the cyst ruptured and collapsed spontaneously during follow-up. It is emphasized that the presence of this lesion, which was more frequent than previously expected, should be kept in mind when diagnosing pineal tumors and should not be misdiagnosed. Surgery should not be undertaken unless the lesion produces symptoms due to the compression of the quadrigeminal plate, aqueduct, or the vein of Galen.
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  • 34
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    Child's nervous system 5 (1989), S. 371-373 
    ISSN: 1433-0350
    Keywords: Temporal encephalocele ; Cerebral angiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An unusual case of temporal encephalocele is presented in this report. A large temporal mass was detected prenatally by ultrasound and following delivery by caesarian section. It was determined to be a large temporal encephalocele with extensive invasion into the subtemporal, facial and cervical regions. This case is presented because of the unique pathology of this congenital malformation and the extensive surgery that was required. The management and the clinical and radiological features are discussed.
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  • 35
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    European archives of psychiatry and clinical neuroscience 238 (1989), S. 225-230 
    ISSN: 1433-8491
    Keywords: Magnetic resonance imaging ; Friedreich's ataxia ; Spinal cord atrophy ; MRI evaluation of the brain stem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The severity of Friedreich's ataxia was graded in ten patients by clinical examination and in five by use of posturography. These data were compared with neuroradiology findings. CT-confirmed infratentorial atrophy occured only in advanced cases of Friedreich's ataxia; the correlation with the clinical score was poor. On mid-sagittal MRI planes the diameters of fourth ventricle, brain stem at the level of the inferior olive and spinal cord at the levels of the foramen magnum and C3 were measured. Patients with Friedreich's ataxia had significant MRI-confirmed atrophy of the cranial spinal cord as compared with a normal, age-matched control group. This was also observed in patients with Friedreich's ataxia in the early stages. A reliable correlation between atrophy of the cranial spinal cord and the clinical score, however, could again not be found. MRI exploration of the cranial spinal cord may be recommended as an additional diagnostic marker in Friedreich's ataxia.
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  • 36
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    Journal of neurology 236 (1989), S. 487-488 
    ISSN: 1432-1459
    Keywords: Baló's concentric sclerosis ; Magnetic resonance imaging ; Oligoclonal CSF IgG banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An intra vitam diagnosis of Baló's concentric sclerosis in a 39-year-old male is described. To our knowledge this is the first reported case of ante-mortem diagnosis based solely on magnetic resonance imaging (MRI) findings. MRI showed features unique to this process. After high-dose intravenous therapy with prednisone, the clinical symptoms improved, and MRI showed marked changes of the concentric lesions.
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  • 37
    ISSN: 1432-1459
    Keywords: Status epilepticus ; Computed tomography ; Magnetic resonance imaging ; Single-photon emission computed tomography ; Cerebral oedema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 35-year-old female patient suffering from epilepsy was examined during status epilepticus with simple partial and complex partial seizures by means of EEG, CT, MRI and ictal SPECT. All these examinations showed focal abnormalities with identical location due to oedema and hypervascularisation; these were, however, absent during examinations carried out before and after status epilepticus.
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  • 38
    ISSN: 1619-7089
    Keywords: Bone marrow diseases ; Radionuclide imaging ; Magnetic resonance imaging ; Lymphoma ; Plasmacytoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 63 patients with primary extramedullary malignant lymphoma or plasmacytoma, a study was performed in order to evaluate bone marrow involvement. All patients underwent a 99mTc microcolloid bone marrow whole body imaging (scintigraphy), using a gamma camera interfaced with a computer, followed by nuclear magnetic resonance bone marrow imaging (MRI), (1.5 Tesla). MR images were made of the lumbosacral region, the pelvic region, both femoral and other parts of the skeleton, according to focal lesions in the scintigraphy. A posterior iliac crest bone marrow biopsy was used as a standard reference. In the present study, both scintigraphy and MRI showed a dissiminated or focal involvement or a combination of both. In 53 of the 63 patients (84%) the results were in accordance. Pathological MR signals or pathological findings in scintigraphy did not always correspond to tumorous bone marrow involvement, and were shown to reflect reactive changes in the central part of the skeleton in combination with a periphery radionuclide extention interpreted as a periphery compensatory hematopoetic proliferation. The negative predictive value of scintigraphy and MRI was 92% and 100%, respectively. When combining the results of both examinations, the positive predictive value increased from 49% to 58%, if the bone marrow biopsy is accepted as gold standard. The results indicate that bone marrow investigation performed simultaneously using scintigraphy and MRI is superior both to the use of either of the methods alone and to the traditional iliac crest bone marrow biopsy.
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  • 39
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    Langenbeck's archives of surgery 374 (1989), S. 349-357 
    ISSN: 1435-2451
    Keywords: Magnetic resonance imaging ; Thoracic aortic surgery ; Follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zwecks überprüfung, inwieweit die Kernspintomographie, die mit gutem Erfolg bereits in der präoperativen Diagnostik eingesetzt wird, eine sinnvolle Bereicherung des diagnostischen Instrumentariums bei der postoperativen Kontrolle thorakaler Aortenerkrankungen darstellt, haben wir zwischen dem 1. 4. 1986 und 30. 3. 1988 30 Patienten (20 männlich, 10 weiblich, mittleres Alter 53 Jahre ± 13,7 Jahre) nach Operation an der thorakalen Aorta kernspintomographisch untersucht. Es lagen 19 arteriosklerotische Aneurysmen, 10 Dissektionen sowie ein Tumor der , Aorta descendens vor. In allen 30 Patienten gelang es, kernspintomographisch postoperativ die Ergebnisse der chirurgischen Maßnahmen zu dokumentieren. Es konnten im frühen postoperativen Stadium Komplikationen ausgeschlossen bzw., wie in einem Fall eine retrograde Aortendissektion oder einem anderen ein Hämatoperikard nachgewiesen werden. In der postoperativen Verlaufskontrolle aortaler Dissektionen ließ sich eine aneurysmatische Dilatation der dissezierten Aorta distal der implantierten Prothese in allen Fällen darstellen. Wahres und falsches Lumen konnten differenziert werden. In einem Fall ließ sich die Ausbildung eines Aortenbulbusaneurysmas nachweisen. Zusammengefaßt lassen sich postoperative Komplikationen der thorakalen Aortenchirurgie mit der Kernspintomographie zuverlässig nachweisen und bildlich in 3 Ebenen darstellen. Nichtinvasibilität, das Fehlen einer ionisierenden Strahlung und das ausbleibende Risiko einer Kontrastmittelapplikation machten die Kernspintomographie zu einer idealen Methode für Folgeuntersuchungen nach Operation an der thorakalen Aorta.
    Notes: Summary Operations of the thoracic aorta for aneurysms, dissections, or congenital malformations may lead to early or late complications. Therefore, postoperative control for documentation of the surgical results, for exclusion of early changes and for comparison with later controls is mandatory. To demonstrate that magnetic resonance imaging (MRI), which we already had used with good results for preoperative studies is also able to detect postoperative abnormalities, we examined 30 patients with thoracic aortic disease (20 male, 10 female, mean age 53 ± 13.7 years) with this diagnostic tool. There were 19 arteriosclerotic aneurysms, 10 dissections, and one aortic tumor. With MRI it was possible in all patients to visualize the results of the surgical treatment postoperatively. Early postoperative complications could be excluded, or demonstrated in one case of a retrograde aortic dissection or a hematopericardium. These pathological findings could also be shown by arterial digital subtraction angiography or echocardiography. Using MRI for follow-up of aortic dissections, the development of an aneurysm of the aortic root in a Marfan-patient could be detected. In all these patients, it was possible to differentiate true and false lumen and to detect the origin of major side branches. The diagnostic advantages of MRI, which we compared with other imaging methods, as echocardiography, computed tomography or angiography are that postoperative complications of thoracic aortic aneurysm surgery can be reliably detected and visualized in 3 different planes. Non-invasiveness, the omission of ionizing radiation and no risk of contrast media application underline that magnetical resonance imaging is an ideal method for follow-up after operation of the thoracic aorta.
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  • 40
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    European archives of oto-rhino-laryngology and head & neck 246 (1989), S. 265-268 
    ISSN: 1434-4726
    Keywords: Petrous bone ; Magnetic resonance imaging ; Gadolinium ; Cholesteatoma ; Temporal bone neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty cases of intrapetrous lesions were studied by a 1.5 T magnetic resonance (MR) unit. In all cases, comparisons were made between MR, CT and clinical findings. Our present material included 9 cholesteatomas, 1 cholesterol cyst, 3 primary epidermoid carcinomas, 2 metastatic neoplasms, 1 glomus jugulare tumor and 4 facial neurinomas. Gadolinium was injected in 7 cases and seemed to be the best method for studying the intrapetrous tumors. MR permitted accurate topographic study and assessment of tumoral extension, as well as a ready demonstration of tumor vascularity. The present findings also showed that MR is not capable of defining small bony detail or calcifications.
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  • 41
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 19-24 
    ISSN: 0009-2940
    Keywords: Bis(diorganoboryl)chalcogenides ; Pyrazaboles ; Pyrazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Neuartige Substituierte B2ElVIN2 HeterocyclenDie Bis(diorganoboryl)chalkogenide (R2B)2O [R = C2H5 (3); R2 = 1,5-C8H14 (1)], (R2B)2S [R2 = 1,5-C8H14 (5)], und (R2B)2Se [R2 = 1,5-C8H14 (7)] reagieren mit Pyrazol (Pz) und dessen Derivaten 3-Methylpyrazol (3-MePz) und Indazol (benzo-Pz) in hohen Ausbeuten (65-92%) zu stabilen 1:1-Additionsverbindungen [z. B. 2 (El = O), 4 (El = O), 6 (El = S), 8 (El = Se)]. 1H-, 13C-, 11B-NMR-Spektren und Röntgenstrukturanalysen (von 2 und 6) zeigen eine Grundstruktur mit einem zentralen B2ElN2-Heterocyclus (El = O, S, Se). Die Reaktion von 2 mit R2BH und die Thermolyse von 4 führen zu den dimeren 1-Pyrazolylboranen 9a bzw. 9b.
    Notes: The bis(diorganoboryl) chalcogenides (R2B)2O [R = C2H5 (3); R2 = 1,5-C8H14 (1)], (R2B)2S [R2 = 1,5-C8H14 (5)], and (R2B)2Se [R2 = 1,5-C8H14 (7)] react with pyrazole (Pz) and its derivatives 3-methylpyrazole (3-MePz) and indazole (benzo-Pz) to form in high yields (65-92%) stable 1:1 adducts [e.g. 2 (El = O), 4 (El = O), 6 (El = S) and 8 (El = Se)]. 1H-, 13C-, 11B-NMR spectra and X-ray analyses (of 2 and 6) show a basic structure with a central B2ElN2 (El = O, S, Se) heterocycle. The reaction of 2 with R2BH and the thermolysis of 4 give the dimeric 1-pyrazolylboranes 9a and 9b, respectively.
    Additional Material: 3 Ill.
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  • 42
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 31-36 
    ISSN: 0009-2940
    Keywords: Mercury - mercury contacts ; Naphthalenediylmercury compounds ; Organomercury compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Extremely Short Mercury-Mercury Contacts in peri-Dimercurated Naphthalene Compounds1-Naphthylmercury chloride (1) and 1,8-naphthalenediylbis(mercury chloride) (2) were prepared from the corresponding naphthyllithium precursors and HgCl2 in ca. 80% yield. In an alternative route, 2 can be obtained from 1,8-naphthalenediyldiboric acid anhydride and HgCl2 in 85% yield. The structure of 2·DMSO has been determined by X-ray diffraction methods. The lattice contains discrete adducts in which the two mercury atoms are bridged by the DMSO oxygen atom. The HgCl moieties are bent away from each other through distortions of the naphthalene framework and of the C—Hg—Cl axes, which results in a Hg ‥ Hg distance of 3.102(1) Å. - Symmetrization of 2, induced by treatment with NaI in aqueous ethanol, affords bis(μ-1,8-naphthalenediyl)dimercury (3). In the X-ray structure determination of this compound the shortest „non-bonding“ Hg·Hg contact reported in the literature has been detected: Hg1··Hg2 = 2.797(1) Å. The molecule also shows distortions in the naphthalene framework and in the C—Hg—C axes [C—Hg—C = 173.3(5)°].
    Notes: 1-Naphthylquecksilberchlorid (1) und 1,8-Naphthalindiylbis-(quecksilberchlorid) (2) werden aus den zugehörigen Naphthyllithium-Verbindungen und HgCl2 mit ca. 80% Ausbeute erhalten. Alternativ kann 2 auch aus 1,8-Naphthalindiyldiborsäureanhydrid und HgCl2 gewonnen werden (Ausbeute 85%). Von 2·DMSO wurde die Kristallstruktur bestimmt. Es liegen diskrete Addukte vor, in denen die beiden Hg-Atome durch das O-Atom des DMSO überbrückt werden. Die HgCl-Einheiten sind durch Verzerrungen im Naphthalingerüst, durch Winkelung der Achsen C—Hg—Cl und durch deren Auslenkung aus der Naphthalinebene voneinander weggebogen, so daß ein Hg·· Hg-Kontakt von 3.102(1) Å resultiert. - 2 symmetrisiert sich bei der Einwirkung von NaI in wäßrigem Ethanol unter Bildung von Bis(μ-1,8-naphthalindiyl)diquecksilber (3). Bei der Strukturanalyse dieser im Kristall zentrosymmetrischen Verbindung wurde der bisher kürzeste „nichtbindende“ Hg··Hg-Kontakt von 2.797(1) Å gefunden. Auch in 3 sind die C—Hg—C-Achsen abgewinkelt [C—Hg—C = 173.3(5)°], und das Naphthalingerüst ist verzerrt.
    Additional Material: 6 Ill.
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  • 43
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 59-61 
    ISSN: 0009-2940
    Keywords: N-Butyl-N′-dansylthiourea ; Complexing agent, fluorescent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Butyl-N′-dansylthiourea as Fluorescent Broad-Band Complexing AgentN-Butyl-N′-dansylthiourea (2) [dansyl = 5-(dimethylamino)-1-naphthylsulfonyl] is obtained by the reaction of dansylamide (1) with butyl isothiocyanate. The compound is a stable, fluorescent complex agent for a broad spectrum of metal ions. The UV spectra and fluorescence of the ligand and some metal complexes are discussed. The fluorescence of the dansyl group is strongly affected by metal ions.
    Additional Material: 3 Ill.
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  • 44
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 83-94 
    ISSN: 0009-2940
    Keywords: Enaminecarbaldehydes ; Enamino ketones ; hetero Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Struktur von Enaminecarbaldehyden und Enamino KetonenDie Synthese der Enamincarbaldehyde 1a-s und 17a-c sowie der Enamino-Ketone 2a-k und deren N-Acyl-Derivate 19a-k und 21-t mit Elektronenacceptor-Substituenten an C-2 bzw an der CO-Gruppe wird beschrieben. Kondensation von 2-Formyl-3-oxopropansäure-methylester (13) mit Ammoniak und den Aminen 14b-s ergab die Enamincarbaldehyde 1a bzw. 1b-s in einer Ausbeute von 72-93%. Die Enamincarbaldehyde 17 konnten durch Formylierung von 15 mit dem gemischten Ameisensäureessigsäureanhydrid erhalten werden. Die Synthese der Enamino-Ketone 2a-k erfolgte mit einer Ausbeute von 61-97% durch Kondensation von Ammoniak und Aminen mit den Enolethern 24a-f, die durch Umsetzung reaktiver Acylchloride 23 mit Ethylvinyl-ether dargestellt wurden. Die für hetero-Diels-Alder-Reaktionen benötigten N-Acyl-Derivate 19a-k und 21-t wurden durch Acylierung des Enamincarbaldehyds 1a und der Enamino-Ketone 2a-k gebildet.
    Notes: The synthesis of enaminecarbaldehydes 1a-s and 17a-c as well as enamino ketones 2a-k, and their N-acyl derivatives 19a-k and 21-t with electron accepting substituents at C-2 and at the CO group, respectively, is described. Condensation of methyl 2-formyl-3-oxopropanoate (13) with ammonia and the amines 14b-s gave the enaminecarbaldehydes 1a and 1b-s, respectively, in 72-93% yield. The enaminecarbaldehydes 17 were obtained by formylation of 15 with acetic formic anhydride. The synthesis of the enamino ketones 2a-k was accomplished in 61-97% yield by reaction of ammonia and amines with the enol ethers 24a-f, which were formed by treatment of reactive acyl chlorides 23 with ethyl vinyl ether. The enaminecarbaldehyde 1a as well as the enamino ketones 2a-k could be acylated to give 19a-k and 2l-t, respectively, which can be used in the hetero Diels-Alder reaction.
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  • 45
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 119-122 
    ISSN: 0009-2940
    Keywords: Bis(phosphonium) salts ; Pyridylphosphonium salts, tri-n-butyl- and triphenyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Triphenyl-(or Tri-n-butyl-)pyridylphosphonium salts, 2. - 2,4-Pyridinediylbis(phosphonium) Salts2,4-Pyridinediylbis(phosphonium) salts 1 react with nucleophiles to give 4-substituted products 6-8. Under radical reaction conditions the 5-position in 1a is attacked to yield 9. sodium azide transforms 1a into 8. This salt is used as starting material for 11. The removal of the phosphonium groups in 1 and in the resulting products can be carried out selectively.
    Notes: 2,4-Pyridindiylbis(phosphoniumsalze) 1 lassen sich mit nucleophilen Reaktionspartnern in die 4-substituierten Produkte 6-8 überführen. Unter radikalischen Bedingungen wird selektiv die 5-Position in 1a unter Bildung von 9 angegriffen. Nach Umsetzung mit Natriumazid entsteht zunächst das Salz 8, das als Ausgangsverbindung für 11 dient. Die Substitution der Phosphoniumgruppen aus den Edukten 1 und Produkten kann selektiv durchgeführt werden.
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  • 46
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 145-149 
    ISSN: 0009-2940
    Keywords: Cycloalkenes, 1-methyl- ; Ozonolysis ; Peroxyhemiacetals, cyclic ; Rubber, natural ; Tetrahydrofurans, 2-hydroperoxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ozonolyses of 1-Methylcyclopentene, 1-Methylcyclobutene, 5-Hexen-2-one and Natural Rubber in the Presence of MethanolOzonolyses of 1-methylcyclopentene (8a) and of 1-methylcyclobutene (8b) in methanol proceeded in each case in the two possible directions. The resulting methoxyperoxides 13 and 14 afforded the corresponding peroxyhemiacetals 15 and 19 by intramolecular reactions of the OOH with the corresponding carbonyl groups. Ozonolysis of 1-methylcyclobutene (8b) additionally gave the corresponding ozonide 17b and 2-hydroperoxy-5-methoxy-2-methyl-as well as 5-hydroperoxy-2-methoxy-2-methyltetrahydrofuran (16b and 18b). The mode of formation of these hydroperoxy compounds has been elucidated by ozonolyses of 5-hexen-2-one (25) and of natural rubber (28) in the presence of methanol.
    Notes: Ozonolysen von 1-Methylcyclopenten (8a) und von 1-Methylcyclobuten (8b) in Methanol verliefen jeweils nach beiden möglichen Spaltungsrichtungen. Die dabei gebildeten Methoxyhydroperoxide 13 und 14 ergaben durch intramolekulare Reaktionen der OOH- mit den Carbonylgruppen die entsprechenden Peroxyhalbacetale 15 bzw. 19. Bei der Ozonolyse von 1-Methylcyclobuten (8b) wurden zusätzlich das entsprechende Ozonid 17b sowie 2-Hydroperoxy-5-methoxy-2-methyl- und 5-Hydroperoxy-2-methoxy-2-methyltetrahydrofuran (16b und 18b) gebildet. Die Bildungsweise dieser Hydroperoxy-Verbindungen wurde durch Ozonolysen von 5-Hexen-2-on (25) und von Naturkautschuk (28) im Beisein von Methanol aufgeklärt.
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  • 47
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 169-174 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of New 3-substituted PyrrolesThe synthesis of 3-alkyl- (4), 3-(ω-bromoalkyl)- (5), 3-iodo- (6), 3-formyl- (9a), 3-acetyl-1-(triisopropylsilyl)pyrrole (9b), of 2-[1-(triisopropylsilyl)-3-pyrrolyl]-2-propanol (7), 1-(triisopropylsilyl)-3-pyrrolecarboxylic acid (8), and 7-[1-(triisopropylsilyl)-3-pyrrolyl]heptanoic acid (10) as well as the desilylation of these products to the corresponding 3-substituted pyrroles 11 is described. Intermediates in these syntheses are 1-(triisopropylsilyl)pyrrole (1), 3-bromo- (2), and 3-lithio-1-(triisopropylsilyl)pyrrole (3).
    Notes: Die Synthese von 3-Alkyl- (4), 3-(ω-Bromalkyl)- (5), 3-Iod- (6), 3-Formyl- (9a) und 3-Acetyl-1-(triisopropylsilyl)pyrrol (9b), von 2-[1-(Triisopropylsilyl)-3-pyrrolyl]-2-propanol (7), 1-(Triisopropylsilyl)-3-pyrrolcarbonsäure (8) und 7-[1-(Triisopropylsilyl)-3-pyrrolyl]heptansäure (10) sowie die Desilylierung dieser Produkte zu den entsprechenden 3-substituierten Pyrrolen 11 wird beschrieben. Zwischenstufen der Darstellung sind 1-(Triisopropylsilyl)pyrrol (1), 3-Brom- (2) und 3-Lithio-1-(triisopropylsilyl)pyrrol (3).
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  • 48
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    Berichte der deutschen chemischen Gesellschaft 122 (1989) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 223-230 
    ISSN: 0009-2940
    Keywords: Gold(I) silyl complexes ; Transition-metal silyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition-Metal Silyl Complexes, 26. - Gold(I) Silyl ComplexesComplexes of type L-Au-SiR3 with L = PR′3 or PhNC and SiR3 = Si(aryl)3, Si(SiMe3)3, or SiPh2Me are prepared by reaction of L-Au-Cl with LiSiR3. Depending on L and R, their stability decreases, in the order R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Reaction of R′3P-Au-CH3 or R′3P-Au-OAc with HSiR3 does not yield silyl complexes. However, using chlorinated silanes like HSiR2Cl, CH3/Cl or OAc/Cl exchange takes place. The Mössbauer spectrum of MePh2P-Au-SiPh3 (6) and NMR- and IR-spectroscopic investigations show that silyl groups act as strong σ donors towards the gold atom. MePh2P-Au-SiPh3 (6) and MePh2P-Au-Si(SiMe3)3 (7) have been characterized by X-ray structure analyses [Au—Si 235.4(4) and 235.6(2) pm]. The Au-Si bond in MePh2P-Au-SiPh2Tol (5) is cleaved by X2 (X = Cl, Br, I), HCl or MeI, but not by H2O or MeOH.
    Notes: Komplexe des Typs L-Au-SiR3 mit L = PR′3 oder PhNC und SiR3 = Si(aryl)3, Si(SiMe3)3 oder SiPh2Me wurden durch Umsetzung von L-Au-Cl mit LiSiR3 dargestellt. Ihre Stabilität sinkt in Abhängigkeit von L und R in der Reihenfolge R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Umsetzung von R′3P-Au-CH3 oder R′3P-Au-OAc mit HSiR3 ergibt keine Silyl-Komplexe, bei Verwendung chlorierter Silane, HSi-R2Cl, findet lediglich CH3/Cl- bzw. OAc/Cl-Austausch statt. Das Mößbauer-Spektrum von MePh2P-Au-SiPh3 (6) sowie NMR- und IR-spektroskopische Untersuchungen zeigen, daß Silylreste als starke σ-Donor-Liganden gegenüber dem Goldatom wirken. MePh2P-Au-SiPh3 (6) und MePh2P-Au-Si(SiMe3)3 (7) wurden durch Röntgenstrukturanalysen charakterisiert [Au—Si 235.4(4) und 235.6(2) pm]. Die Au—Si-Bindung in MePh2P-Au-SiPh2 Tol (5) wird durch X2 (X = Cl, Br, I), HCl oder MeI, nicht aber durch H2O oder MeOH gespalten.
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  • 50
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 245-252 
    ISSN: 0009-2940
    Keywords: Germylenes ; Germanium nitrogen compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Germylenes with Azides: Iminogermanes, Azidogermanes, Tetrazagermoles and HexaazadigermadispirododecanesGermylenes, X2Ge, stabilized by steric blocking and/or incorporation into five-membered ring systems, react with azido compounds YN3 depending on the steric requirements of the substituents X and Y to give iminogermanes, X2Ge=NY (1, 2) azidogermanes X2Ge(N3)NY2 (6-8) tetrazagermoles, X2Ge(— NY — N =)2 (10-16), and hexaazadigermadispirododecanes, [(— NR — CH2 — CH2 — NR —)Ge(μ-NY -)]2 (17, 18). NMR (1H, 13C, 14N, 15N, and 29Si), MS data, and X-ray structure analyses of the compounds 8, 9, 16, and 18 are reported.
    Notes: Durch sterische Blockierung und/oder Einbau in fünfgliedrige Ringsysteme stabilisierte Germylene, X2Ge, reagieren mit Azidoverbindungen, YN3, in Abhängigkeit von der Raumerfüllung der Substituenten X und Y zu Iminogermanen X2 Ge=NY (1, 2), Azidogermanen, X2Ge(N3)NY2 (6′8), Tetrazagermolen, X2Ge-(-NY-N=)2 (10-16), bzw. Hexaazadigermadispirododecanen, [(—NR—CH2—CH2—NR— )Ge(μ-NY-)]2 (17, 18). NMR-(1H, 13C, 14N, 15N und 29Si), MS-Daten und Röntgenstrukturanalysen für die Verbindungen 8, 9, 16 und 18 sind angegeben.
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  • 51
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 271-277 
    ISSN: 0009-2940
    Keywords: Chalcogenogermanes, (trifluoromethyl)- ; Disilaselenanes ; Germachalcogenanes, bis(trifluoromethyl)- ; Germanes, (trifluoromethyl)- ; Germatranes, (trifluoromethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (Trifluormethyl)germanes, III. - Preparation of New (Trifluormethyl)germanium Chalcogene CompoundsStarting with the dihalogenobis(trifluoromethyl)germanes (CF3)2-GeX2 (X = Cl, or I), halogen-chalcogen exchange leads to corresponding chalcogen derivatives of the general type [(CF3)2GeE]n (6, 7) (E = O, NH, S, or Se). The resulting compounds differ in their degree of polymerisation. [(CF3)2GeO]x and the corresponding sesquioxane [(CF3)GeO1, 5]x are highly polymeric, quite in contrast to the corresponding germathianes and -selenanes. The crystal structure of [(CF3)2GeO]x (6a) was determined by X-ray single crystal diffraction. The reaction of CF3GeCl3 with triethanolamine results in the formation of 1-(trifluoromethyl)germatrane (13). Disilaselenane (10) reacts at low temperatures with chloro-(trifluoromethyl)germanes (CF3)nGeCl4-n under retention of one Si—Se bond to give (CF3)nGe(SeSiH3)4-n (11) and H3SiCl. Compounds with n = 3 and 2 could be isolated. Exchange of iodine by ECF3 takes place with iodogermanes (CF3)nGeI4-n and Hg(ECF3)2 (E = S, Se) with formation of a complete series of (trifluoromethyl)(trifluoromethylchalcogeno)germanes (CF3)nGe-(ECF3)4-n (3, 5).
    Notes: Durch Halogen-Chalkogen-Austauschreaktionen an (CF3)2)GeX2 (X = Cl, I) wurden Bis(trifluormethyl)germachalkogenane [(CF3)2GeE]n (6, 7) E = O, NH, S, Se) von unterschiedlichem Oligomerisierungsgrad erhalten. Die Germoxane [(CF3)2GeO]x und (CF3GeO1,5)x sind im Gegensatz zu den homologen Germathianen und -selenanen polymer, wobei die Struktur von [(CF3)2GeO]x (6a) durch eine Kristallstrukturanalyse ermittelt wurde. Durch Umsetzung von CF3GeCl3 mit Triethanolamin wird 1-(Trifluormethyl)germatran (13) erhalten. Disilaselenan (10) reagiert bei tiefen Temperaturen mit den Chlor (trifluormethyl)-germanen (CF3)nGeCl4-n monofunktionell unter Erhalt einer Si—Se-Bindung zu (CF3)nGe(SeSiH3)4-n (11) und H3SiCl, von denen die Verbindungen mit n = 3 und 2 isoliert werden konnten. Reaktionen der Iodgermane (CF3)nGeI4-n(1) mit Hg(ECF3)2) (E = S, Se) führen unter Substitution des Iods gegen die ECF3-Gruppen zur vollständigen Reihe der (Trifluormethyl)(trifluormethylchalkogeno)germane (CF3)nGe(ECF3)4-n (3, 5).
    Additional Material: 3 Ill.
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  • 52
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 291-292 
    ISSN: 0009-2940
    Keywords: (Phthalocyaninato)copper complex, substituted with crown ethers ; Alkali metal extraction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A soluble (phthalocyaninato)copper(II) complex containing eight symmetrical benzo-15-crown-5 substituents, namely {2,3,9,10,16,17,23,24-octakis[[benzo-15-crown-5)-4′ -yl]oxymethyl]phthalocyaninato}copper(II) (2) from 1,2-bis{[benzo-15-crown-5)-4′-yl]oxymethyl}-4,5-dibromobenzene (1) and CuCN in quinoline or pyridine was synthesized. The crown-ether groups in 2 were shown to prefer intramolecular complexation with alkali metal ions.
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  • 53
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 463-466 
    ISSN: 0009-2940
    Keywords: C—C Rotation ; Sterical hindrance by SF5 groups ; Rotational barriers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterical Hindrance of the C—C Rotation by two SF5 GroupsAddition of SF5Cl to SF5CH=CF2 gives products carrying two SF5 groups on one carbon atom. As a consequence, C—C single bond rotation is strongly hindered. The highest rotational barrier observed is 61.7 kJ mol-1, rotational isomers are hence detectable at room temperature.
    Notes: Die Addition von SF5Cl an SF5CH=CF2 ergibt Produkte, die zwei SF5-Gruppen an einem Kohlenstoff tragen. In diesen kommt es zu einer starken Hinderung der Rotation um die C—C-Einfachbindung. Die höchste Rotationsbarriere wird mit 61.7 kJ mol-1 gefunden, d. h. Rotationsisomere sind bei Raumtemperatur getrennt nachweisbar.
    Additional Material: 4 Ill.
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  • 54
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 467-472 
    ISSN: 0009-2940
    Keywords: Tetracarbonylchromium complexes ; 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborine derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Structure, and Reactions of 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborine DerivativesThe 1,2,3,6-tetrahydro-1,2,3,6-diphosphadiborine derivatives 3a and 3b are obtained by cyclocondensation of 1,2-bis[chloro(dialkylamino)boryl]ethenes 2 and 1,2-dipotassium 1,2-di-tert-butyldiphosphanediide. As in the case of 2,5-dihydro-1H-1,2,5-phosphadiborole derivatives 1 the temperature-dependent 1H-NMR spectra of 3b exhibit a lowered barrier of inversion at phosphorus. The X-ray structure analysis of 3b shows, that the six-membered C2B2P2 ring is nonplanar and the P atoms are coordinated pyramidally. Attempts to substitute the dialkylamino groups at the boron atoms of 3a and 3b with HCl·Et2O or tBuLi lead to cleavage of the B—P bonds. Reaction between 3a or 3b and Cr(CO)3(MeCN)3 does not result in the formation of tricarbonylchromium complexes but of tetracarbonylchromium complexes 6a and 6b with pentahapto-bonded ligands 3a and 3b.
    Notes: Die 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborin-Derivate 3a und 3b entstehen durch Cyclokondensation aus 1,2-Bis[chlor(dialkylamino)boryl]ethenen 2 und 1,2-Dikalium-1,2-di-tert-butyldiphosphandiid. Die Temperaturabhängigkeit der 1H-NMR-Spektren von 3b dokumentiert wie bei 2,5-Dihydro-1H-1,2,5-phosphadiborol-Derivaten 1 eine erniedrigte Phosphor-Inversionsbarriere. Die Röntgenstrukturanalyse von 3b zeigt, daß der C2B2P2-Sechsring im Kristall nicht eben ist und daß die P-Atome pyramidal koordiniert sind. Versuche zur Substitution der Dialkylaminogruppen an den Boratomen von 3a und 3b mit HCl·Et2O oder tBuLi führen zur Spaltung der B—P-Bindungen. Die Umsetzung von 3a bzw. 3b mit Cr(CO)3(MeCN)3 ergibt keine Tricarbonylchrom-Komplexe, sondern die Tetracarbonylchrom-Komplexe 6a bzw. 6b, in denen die Liganden 3a und 3b pentahapto gebunden sind.
    Additional Material: 7 Tab.
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  • 55
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Synthesis via Transition Metal Complexes, 34. - Novel Formation of C=C Bonds by Condensation of Acid Amides with Carbene Complexes Involving an Insertion of C2 Units into M=C BondsCarben complexes LnM=C(OEt)C6H5 1 [LnM = Cr(CO)5, Mo(CO)5, W(CO)5] and acid amides RCH2CONMe2 2 undergo a novel condensation reaction in presence of POCl3/Et3N to give alkenyl aminocarbene complexes 3. The reaction involves an insertion of a C2 unit of 2 into the M=C bond of 1 to give a C=C bond. It can be achieved with open-chain and cyclic amides like N-methyl-2-pyrrolidone (8). the structures of the complexes have been determined spectroscopically. A mechanism of the reaction is suggested.
    Notes: Carbenkomplexe LnM=C(OEt)C6H5 1 [LnM = Cr(CO)5, Mo(CO)5, W(CO)5] lassen sich mit Säureamiden RCH2CONMe2 2 und POCl3/Et3N zu Alkenyl-Aminocarben-Komplexen 3 kondensieren. Dabei wird eine C2-Einheit von 2 in die M=C-Bindung von 1 eingeschoben und eine C=C-Bindung neu geknüpft. Die Reaktion gelingt mit offenkettigen und cyclischen Amiden wie N-Methyl-2-pyrrolidon (8). Die Strukturen der Komplexe wurden spektroskopisch ermittelt und Vorschläge zur Deutung des Reaktionsablaufs gemacht.
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  • 56
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 711-714 
    ISSN: 0009-2940
    Keywords: Azulenes ; 1,6-Methano[10]annulenes ; 1,2,4,5-Tetrazine ; [4 + 2] Cycloadditions, „inverse“ ; Pyridazines, annulated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azulene and 1,6-Methano[10]annulene as Dienophiles in the Diels-Alder Reaction with 3,6-Bis(trifluoromethyl)-1,2,4,5-tetrazineThe LUMO-diene-controlled [4 + 2] cycloadditions of azulene (2) and 1,6-methano[10]annulene (14) with the electron-deficient s-cisfixed diazadiene system of 3,6-bis(trifluoromethyl)-1,2,4,5-tetrazine (1) are described. Contrary to expectation, 1 reacts under unusually mild conditions with 2 (or its valence tautomer 3) to yield the adduct 4 which after N2 elimination rearranges to the benzo[f]phthalazine 11. The Diels-Alder reaction of 1 with 14 (or its valence tautomer 13) leads to the annulated dihydropyridazines 15 and 16, which can be dehydrogenated by silver(I) oxide to the methano-bridged aromatic cyclodecapyridazine 17 and the olefinic phthalazino[5,6-f]phthalazine 18, respectively. Besides, the methano-bridged cyclodeca[d]pyridazine 24 is prepared.
    Notes: LUMO-Dien-kontrollierte [4 + 2]-Cycloadditionen von Azulen (2) und 1,6-Methano[10]annulen (14) an das elektronenarme, s-cis-fixierte Diazadiensystem von 3,6-Bis(trifluoromethyl)-1,2,4,5-tetrazin (1) werden beschrieben. Wider Erwarten reagiert 1 unter ungewöhnlich milden Bedingungen mit 2 (oder dessen Valenztautomerem 3) zum Addukt 4, das nach N2-Eliminierung und nachfolgender Umlagerung das Benzo[f]phthalazin 11 liefert. Die Diels-Alder-Reaktion von 1 mit 14 (oder dessen Valenztautomer 13) führt zu den beiden anellierten Dihydropyridazinen 15 und 16, die mit Silber(I)-oxid zu dem Methano-überbrückten aromatischen Cyclodecapyridazin 17 bzw. dem olefinischen Phthalazino[5,6-f]phthalazin 18 dehydriert werden können. Daneben wird das Methano-überbrückte Cyclodeca[d]pyridazin 24 dargestellt.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 715-719 
    ISSN: 0009-2940
    Keywords: Alkyne ; Carbene ; Cycloisomerization ; Pyrolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die thermische Cycloisomerisierung langkettiger Alkylacetylene in der GasphaseDie thermische Cycloisomerisierung einiger Alkylacetylene wurde in einem Laborrohrreaktor aus Quarzglas untersucht. 1-Hexin (1) wird dabei durch 1,2-H-Verschiebung und 1,5-C,H-Insertion des intermediär gebildeten Pentylidencarbens (vgl. Schema 1) in 3-Methyl-1-cyclopenten (5) umgelagert. 5-Methyl-1-hexin (2) reagiert analog; es entsteht 3,3-Dimethyl-1-cyclopenten (6). Im Gegensatz zur Bildung von in 3-Stellung methylierten Cyclopentenen aus 1-Alkinen ensteht aus 2-Hexin (3) 1-Methyl-1-cyclopenten (7). Offenbar ist die Acetylen-Vinyliden-Umlagerung nicht auf 1,2-H-Verschiebung beschränkt. Der Mechanismus der Cycloisomerisierung von Alkylacetylenen wird durch Untersuchungen mit D-markierten Alkinen bestätigt. Die Ergebnisse lassen den Schluß zu, daß die Cycloisomerisierung ohne weiteres mit dem überwiegend nach einem Radikalketten-Mechanismus verlaufenden thermischen Zerfall konkurrieren kann.
    Notes: The thermal cycloisomerization of some alkylacetylenes was investigated in a tubular quartz reactor. At 570°C 1-hexyne (1) rearranges to 3-methyl-1-cyclopentene (5) with a selectivity of about 27 by a reaction sequence including an acetylene-vinylidene rearrangement and 1,5-C,H insertion of the intermediately formed alkylidenecarbene species. 5-methyl-1-hexyne (2) behaves analogously forming 3,3-dimethyl-1-cyclopentene (6), while 2-hexyne (3) provides 1-methyl-1-cyclopentene (7) indicating that the acetylene-vinylidene rearrangement is obviously not restricted to 1,2-H shifts. The mechanism of the cycloisomerization of alkylacetylenes is investigated by means of D-labeled parent alkynes. The results show that the unimolecular cycloisomerization via alkylidenecarbenes obviously can be an important channel despite the dominance of a radical chain course.
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  • 58
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 745-748 
    ISSN: 0009-2940
    Keywords: Flash Pyrolysis ; Matrix IR spectroscopy ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methoxy- und AminoisocyanatMethoxyisocyanat (1) kann durch Photolyse von Azidoameisensäure-methylester (3) oder Pyrolyse von N-Methoxycarbonyl-O-methylhydroxylamin (4) dargestellt werden. Aminoisocyanat (2) ist auf ähnliche Weise durch Photolyse von Carbamoylazid (12) und Pyrolyse von Carbazinsäure-methylester (13) oder 3,4-Diaminofurazan (14) zugänglich. Die IR-Spektren von 1 und 2, aufgenommen in einer Argon-Matrix bei 10 K, werden diskutiert.
    Notes: Methoxyisocyanate (1) can be prepared by photolysis of methyl azidoformate (3) or pyrolysis of N-methoxycarbonyl-O-methyl-hydroxylamine (4). Aminoisocyanate (2) is similarly formed on photolysis of carbamoyl azide (12) and pyrolysis of either methyl carbazate (13) or 3,4-diaminofurazan (14). The infrared spectra of 1 and 2 in an argon matrix at 10 K have been measured, and some of their properties are discussed.
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  • 59
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 749-752 
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Photochemistry ; Theoretical vibrational spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Infrarot-Spektren und Photochemie von Isodiazen und seinen deuterierten IsotopomerenDie Matrixisolation von Aminoisocyanat eröffnet einen neuen ergiebigen Weg zur Darstellung von Isodiazen (Aminonitren). Damit ist es möglich geworden, nicht nur sein IR-Spektrum eindeutig festzulegen und mit Hilfe von ab-initio-Rechnungen zu interpretieren, sondern auch seine Photochemie zu untersuchen.
    Notes: The matrix isolation of aminoisocyanate opens a new efficient route for the preparation of isodiazene (aminonitrene). Its infrared spectrum can now, with the help of ab initio calculations, be interpreted, and its photochemistry can be studied.
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  • 60
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 795-796 
    ISSN: 0009-2940
    Keywords: Thiochalcones ; Thienylchalcones ; Fries rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four new thienylchalcones (1, 4, 5, and 6) were synthesized by condensing hydroxy-nitroacetophenones with 2-thiophene and 3-thiophenecarboxaldehydes in the presence of dilute NaOH.
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  • 61
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 767-779 
    ISSN: 0009-2940
    Keywords: Molecular twisting ; cis-9,10-Dihydronaphthalenes, persubstituted ; Valence isomerizations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Valence Isomerizations, 17. - Persubstituted cis-9,10-Dihydronaphthalenes and their Valence IsomerizationsThe tricyclic diester 10 is available from 2-butyne in a six-step synthesis with an overall yield of 10%. Thermolysis of 10 gives the bicyclic diester 11 which upon UV irradiation yields 12 as the first persubstituted cis-9,10-dihydronaphthalene. X-ray analysis of 12 shows the molecule considerably twisted along the central bond. In addition, the planes of the ester groups are at an angle of approximately 60° to the „planes“ of the six-membered rings so that conjugation of the diene systems with the carbonyl functions is virtually interrupted, an effect which is reflected by the unusual spectroscopic properties of 12. The same structural features can be found in decamethyl-cis-9,10-dihydronaphthalene (16). When heated slightly, 12 is converted to the tetracyclic valence isomer 34. On reduction of 12 with diisobutylaluminum hydride both, dihydronaphthalene dicarbinol 25 as well as its unexpected positional isomer 26, are formed depending on the reaction conditions. Etherification of the reduction products with CH2N2/Et2O—BF3 furnishes a mixture of the three isomeric bis(methoxymethyl) compounds 31, 32 and 33. They can be separated by chromatography in the cold, but revert to the mixture of the three isomers at room temperature. We consider diradical 38 to be the intermediate of this intriguing valence isomerization.
    Notes: Der tricyclische Diester 10 ist in sechs Stufen in einer Gesamtausbeute von 10% aus 2-Butin zugänglich. Thermolyse von 10 liefert den Bicyclus 11, bei dessen UV-Bestrahlung das erste persubstituierte cis-9,10-Dihydronaphtalin 12 gebildet wird. Eine Röntgenstrukturanalyse von 12 beweist die starke Verdrillung des Moleküls um die zentrale Bindung. Die Ebenen der Ester-Gruppen stehen ungefähr in einem 60°-Winkel zu den Sechsring-„Ebenen“, so daß die Konjugation der Dien-Systeme mit den Carbonyl-Funktionen praktisch unterbrochen ist, ein Effekt, der sich in den ungewöhnlichen spektroskopischen Eigenschaften von 12 widerspiegelt. Analoge Strukturmerkmale gelten auch für das Decamethyl-cis-9,10-dihydronaphthalin (16). Bicyclus 12 wandelt sich bei leichtem Erwärmen in den valenzisomeren Tetracyclus 34 um. Reduktion von 12 mit Diisobutylaluminiumhydrid gibt je nach den Reaktionsbedingungen das Dihydronaphthalindicarbinol 25 bzw. das unerwartete Stellungsisomere 26. Veretherung der Reduktionsprodukte mit CH2N2/Et2O—BF3 liefert ein Gemisch der drei isomeren Bis(methoxymethyl)-Verbindungen 31, 32 und 33, die chromatographisch in der Kälte trennbar sind, aber schon bei Raumtemperatur wieder das Gemisch der drei Isomeren zurückbilden, wobei das Diradikal 38 als Zwischenprodukt dieser erstaunlichen Valenzisomerisierung anzunehmen ist.
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  • 62
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 803-808 
    ISSN: 0009-2940
    Keywords: Bismuth organic compounds ; Fluorinated aromatic rings ; Square pyramidal bismuth ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structures of Pentaarylbismuth CompoundsPentaarylbismuth compounds were synthesized by the known reaction Ar3BiX2 + 2 Ar′Li → 2 LiX + BiAr3Ar′2. Whenever possible they were characterized by single-crystal X-ray structure determination. In two cases almost ideal square-pyramidal geometry was found, in a third case there were two different molecules in the unit cell, both again with square-pyramidal geometry. None of these novel bismuth pentaaryls exhibit the deep coloration and the dichroism of Bi(C6H5)5.
    Notes: Pentaarylbismut- Verbindungen wurden durch die bekannte Reaktion BiAr3X2 + 2 Ar′Li → 2 LiX + BiAr3Ar′2 hergestellt und, soweit möglich, durch Röntgenbeugung an Einkristallen strukturell untersucht. In zwei Fällen erwies sich die Struktur als nahezu ideal quadratisch-pyramidal, in einem dritten Fall wurden zwei unterschiedliche Moleküle im Kristall gefunden, die aber beide wiederum quadratisch-pyramidal sind. Keines der hier vorgestellten neuen Bismutpentaaryle zeigt die tiefe Färbung und den Dichroismus von Bi(C6H5)5.
    Additional Material: 5 Ill.
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  • 63
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 533-535 
    ISSN: 0009-2940
    Keywords: Free radicals ; Triphenylmethyl radicals ; ESR measurements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterically Hindered Free Radicals, XIX. - Stable 4,4′,4″-Trisubstituted Triphenylmethyl RadicalsThe title radicals (4-R—C6H4)3C. (1), R = F, Cl, Ph, OMe, NO2, tBu, OEt, SMe, CN, CF3, have been prepared, the latter four for the first time, and the ESR spectra have been recorded. aoH, amH, and apR are listed. The intensities of the ESR signals remain constant within the accessible range of -30 to + 100°C. Within this range these radicals are kinetically stable and do not dimerize like other trityls by, e.g., α,p-, α,o-, α,α -recombinations.
    Notes: Die Titelradikale (4-R—C6H4)3C· (1), R = F, Cl, Ph, OMe, NO2, tBu, OEt, SMe, CN, CF3, wurden dargestellt, davon die vier letzten erstmalig, und mittels ESR-Spektroskopie vermessen. aoH, amH und apR werden angegeben. Die ESR-Signale bleiben im gesamten zugänglichen Temperaturbereich - 30 bis + 100°C in ihrer Intensität unverändert. Daraus folgt, daß alle diese Radikale im genannten Temperaturbereich kinetisch stabil sind, also nicht wie andere Trityle zu Dimerisierungen, etwa α,p-, α,o-, α,α-, neigen.
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  • 64
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 523-531 
    ISSN: 0009-2940
    Keywords: Dicyclopenta-s-indacene ; 2-Osxa[3.3.3]propellane derivatives ; Pentalene derivatives ; [3.3.3]Propellane-3,7-dione ; Weiss reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Novel Products in the Weiss Reaction of 1,2-Cyclopentanedione. Improved Preparation of [3.3.3]Propellane-3,7-dioneThe reaction of 1,2-cyclopentanedione (1c, 9) with the 3-oxoglutarate 4 in methanol/water in the presence of sodium bicarbonate followed by hydrolysis and decarboxylation of the product mixture affords the oxa[3.3.3]propellane ester 11c in addition to the [3.3.3]propellanedione 6c. The alkali enolates of 4 react with 9 in boiling methanol to yield the yellow, poorly soluble alkali dihydropentalenolates 12M and the [3.3.3]propellane tetraester 5c, which on hydrolysis and decarboxylation yields 53% of 6c. The dihydropentalenol 12H equilibrates with the tautomeric β-oxodiester 13, the proportion of which increases with solvent polarity. In methanol solutions, 12H and 13 add diastereoselectively forming the dicyclopenta-s-indacene tetraester syn-14, which is derived from a novel pentacyclic ring system. The configuration of syn-14 is determined by X-ray diffraction analysis. The mechanisms of formation are discussed for 11c, 12M, and syn-14.
    Notes: Nach Umsetzung von 1,2-Cyclopentandion (1c, 9) mit dem 3-Oxoglutarsäureester 4 in Methanol/Wasser in Gegenwart von Natriumhydrogencarbonat, saurer Hydrolyse und Decarboxylierung des Produktgemischs erhält man neben dem [3.3.3]Propellandion 6c den Oxa[3.3.3]propellanester 11c. Die Alkali-Enolate von 4 reagieren mit 9 in siedendem Methanol zu den gelben, schwer löslichen Dihydropentalenolaten 12M und dem [3.3.3]Propellantetraester 5c, der nach Hydrolyse und Decarboxylierung 53% 6c ergibt. Das Dihydropentalenol 12H liegt im Gleichgewicht mit dem tautomeren β-Oxodiester 13 vor, dessen Anteil mit der Polarität des Lösungsmittels zunimmt. In Methanol addieren sich 12H und 13 diastereoselektiv und bilden den Dicyclopenta-s-indacentetraester syn-14, der sich von einem neuartigen, pentacyclischen Ringsystem ableitet. Die Konfiguration von syn-14 wird durch Röntgenstrukturbestimmung aufgeklärt. Die Mechanismen der Bildung von 11c, 12M und syn-14 werden diskutiert.
    Additional Material: 2 Ill.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 553-559 
    ISSN: 0009-2940
    Keywords: Amino acids ; Diastereoselective addition ; 1-(Methacryloyl)proline derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 15. - Diastereoselective Addition of Thiocarboxylic Acids to 1-(Methacryloyl)proline and-prolinol DerivativesThiocarboxylic acids 6 add to 1-(methacryloyl)-substituted proline and prolinol derivatives stereoselectively to give the 1-[3-(acylthio)-2-methylpropionyl]proline and -prolinol derivatives 7,7′ and 9. The less soluble (2S,2′R)-diastereomers are obtained in optical yields ≥ 98% by digestion of the crude products, the configuration of which was determined by acid hydrolysis of (2S,2′R)-7,7′ to (R)-3-mercapto-2-methylpropionic acid [(R)-8]. The stereoselectivity of the additions may be explained by a sevenmembered ring intermediate with an intramolecular H bridge, to which the S-nucleophiles add preferentially to give the compounds with the (2′R)-configuration.
    Notes: Thiocarbonsäuren 6 addieren stereoselektiv mit hohen optischen Ausbeuten an 1-(Methacryloyl)-substituierte Prolin- und Prolinol-Derivate zu den 1-[3-(Acylthio)-2-methylpropionyl]prolin-und -prolinol-Derivaten 7,7′ und 9. Durch Digerieren der Rohprodukte mit Diethylether werden die schwerer löslichen (2S,2′R)-Diastereomeren in optischen Ausbeuten ≥98% erhalten, deren Konfiguration durch Acidolyse von (2S,2′R)-7,7′ zu (R)-3-Mercapto-2-methylpropansäure [(R)-8] bewiesen wurde. Die Stereoselektivität der Additionen wird über einen Siebenring mit intramolekularer H-Brücke als Zwischenstufe, an die Schwefelnucleophile bevorzugt unter Bildung der (2′R)-Konfiguration addieren, gedeutet.
    Additional Material: 10 Tab.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 545-551 
    ISSN: 0009-2940
    Keywords: Amino acids ; Diastereoselective addition ; 1-Acryloylproline esters ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 14. - Diastereoselective Addition of Benzenesulfenyl Chloride to 1-Acryloylproline Esters(S)-Proline esters (S)-1 react with acryloyl chloride (2) to give 1-acryloylproline esters (S)-3 in good yields. Addition of benzenesulfenyl chloride (6) to (S)-3 at -95°C in dichloromethane results in 1-[2-chloro-3-(phenylthio)propionyl]proline esters (2S,2′R/2S,2′S)-7. The diastereoselectivity of the addition depends on the conformer ratio 3′/3″ of the starting material (S)-3. The diastereomers are separated by MPLC. Configuration at C-2′ of the resulting main products (2S,2′S)-7 was proved by independent synthesis. The diastereoselectivity of the addition of 6 to (S)-3 is interpreted to result from formation of a complex of the benzenesulfenyl cation with the proline ester group and subsequent electrophilic addition to a thiiranium intermediate B with (2S,2′R) configuration; the (2S,2′S) diastereomeric adduct 7 then results by nucleophilic attack of chloride at C-2′ under ring opening.
    Notes: Die 1-Acryloylprolinester (S)-3 werden durch N-Acylierung der Prolinester (S)-1 mit Acryloylchlorid (2) in guten Ausbeuten hergestellt; sie addieren Benzolsulfenylchlorid (6) bei -95°C in Dichlormethan mit hoher Diastereoselektivität zu 1-[2-Chlor-3-(phenylthio)propionyl]prolinestern (2S,2′R/2S,2′S)-7, die mittels MPLC getrennt werden. Die Diastereoselektivität der Addition hängt vom Konformerenverhältnis 3′/3″ der Edukte (S)-3 ab. Der Beweis der Konfiguration an C-2′ der als Hauptprodukte anfallenden Diastereomeren (2S,2′S)-7 wird durch eine unabhängige Synthese erbracht. Die Diastereoselektivität der Addition von 6 an (S)-3 wird über eine Komplexbildung des Phenylsulfenylkations mit der Prolinestergruppe und eine sich anschließende elektrophile Reaktion zu einer Thiiranium-Zwischenstufe B mit (2S,2-R)-Konfiguration gedeutet; das (2S,2′S)-diastereomere Additionsprodukt 7 entsteht dann durch nucleophilen Angriff des Chlorids an C-2′ unter Ringöffnung.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 851-855 
    ISSN: 0009-2940
    Keywords: Diphosphines ; Tungsten - tungsten quadruple bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Struktur von W2Cl4{μ(iPr2PCH2CH2CH2PiPr2)}2: Eine durch sperrige, chelatisierende Diphosphane überbrückte Wolfram - Wolfram-VierfachbindungDie Reduktion von WCl4 in THF durch zwei Äquivalente Na/Hg in Gegenwart des sperrigen, chelatisierenden Diphosphinopropans iPr2PCH2CH2CH2PiPr2 (dippp) liefert den violetten, zweikernigen Komplex W2Cl4(μ-dippp)2. Der Komplex besitzt eine W-W-Vierfachbindung und β-Struktur, d.h. die chelatisierenden Diphosphinopropan-Liganden verbrücken die beiden Metall-Zentren. Die 1H-NMR-spektroskopischen Daten zeigen Tieffeldverschiebungen für die dippp-Liganden, die im Einklang mit der β-Struktur stehen. Das 31P{1H}-NMR-Spektrum besteht aus einem Singulett mit 183W-Satelliten. Die Röntgen-Stukturanalyse ergibt für die β-Struktur einen Torsionswinkel P-W-W-P von 75.9° und eine W-W-Bindungslänge von 2.297(1) Å. Aus den Molekülstruktur-Daten und den 1H-NMR-Tieffeldverschiebungen kann die diamagnetische Anisotropie χ der W-W-Vierfachbindung mit - 3000 ± 300 × 10-36 m3/Molekül abgeschätzt werden. Die für den festen Zustand beobachtete Chiralität wird auch in Lösung beibehalten.
    Notes: The reduction of WCl4 in THF by two equivalents of Na/Hg in the presence of the bulky chelating diphosphine iPr2PCH2-CH2CH2PiPr2 (dippp) generates the purple, binuclear complex W2Cl4(μ-dippp)2. The quadruply-bonded molecule has a β structure, that is, the chelating diphosphine bridges the two metal centers. 1H-NMR spectral data show downfield shifts for the ligand protons consistent with the β structure. The 31P{1H}-NMR spectrum consists of a singlet with 183W satellites. The X-ray crystal structure has a twist angle (P-W-W-P torsion angle) of 75.9°, and the W-W bond length is 2.297(1) Å. Using the solidstate data and the observed downfield shifts in the 1H-NMR spectrum, the diamagnetic anisotropy χ has been estimated as - 3000 ± 300 × 10-36 m3/molecule. The chiral structure observed in the solid phase is retained in solution.
    Additional Material: 4 Ill.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 861-864 
    ISSN: 0009-2940
    Keywords: Aminoiminophosphanes ; 1,3,2λ5,4-Thiazaphosphaboretidines ; 1,2,4,3,5-Trithiadiborolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Characterization of 1, 3, 2λ5, 4-ThiazaphosphaboretidinesThe reaction of 1,2,4,3,5-trithiadiborolanes with silylated aminoiminophosphanes leads to the 1,3,2λ5,4-thiazaphosphaboretidines 1a-i. The formation of 1h, i is accompanied by an exchange of the substituents bonded to the N atoms. 1H-, 11B-, 13C-, 29Si-, 31P-NMR, and mass spectra are discussed.
    Notes: Die Umsetzung von 1,2,4,3,5-Trithiadiborolanen mit silylierten Aminoiminophosphanen führt zu den 1,3,2λ5,4-Thiazaphosphaboretidinen 1a-i. Die Bildung von 1h, i wird von einem Austausch der N-ständigen Substituenten begleitet. 1H-, 11B-, 13C-, 29Si-, 31P-NMR- und Massenspektren werden diskutiert.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 857-860 
    ISSN: 0009-2940
    Keywords: Alkenylboranes ; Alkenylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Convenient Route from Alkenylboranes to AlkenylstannanesAlkenyldialkylboranes 1 with various substituents at the C=C double bond, including organometallic groups such as the trimethylstannyl or trimethylsilyl group, react in hexane solution with (diethylamino)- or (dimethylamino)trimethylstannane (2) in the presence of a catalytic amount of lithium dimethyl- or diethylamide (3) to give aminodialkylboranes 4 and alkenyltrimethylstannanes 5 in high yields with retention of the configuration at the C—C double bond. With (diethylamino)trimethylplumbane (2c) the less stable alkenes 5Pb are obtained. A mechanism is proposed, and 1H-, 13C-, 29Si-, 119Sn- und 207Pb-NMR-data are reported.
    Notes: Alkenyldialkylborane 1 mit verschiedenen Substituenten an der C=C-Doppelbindung, einschließlich organometallischer Gruppen wie dem Trimethylstannyl- oder dem Trimethylsilyl-Rest, reagieren in Hexan mit (Diethylamino)- oder (Dimethylamino)trimethylstannan (2) in Gegenwart einer katalytischen Menge von Lithium-diethylamid (3b) oder -dimethylamid (3a) in hoher Ausbeute unter Beibehaltung der Konfiguration an der C—C-Doppelbindung zu den entsprechenden Alkenylstannanen 5 und Aminoboranen 4. Durch Einsatz von (Diethylamino)trimethylplumban (2c) lassen sich die weniger stabilen Alkene 5Pb erhalten. Ein Mechanismus wird vorgeschlagen, und 1H-, 13C-, 29Si-, 119Sn- und 207Pb-NMR-Daten werden mitgeteilt.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1919-1924 
    ISSN: 0009-2940
    Keywords: Hydrogen transfer ; Ziegler catalysis ; Dihydroarenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ziegler Nickel Catalysts for Hydrogen Transfer ReactionsCatalysts prepared from Ni(acac)2 and AlEt3 show high catalytic activity in the hydrogen transfer between dihydroarenes, but hardly any isomerisation and H/D scrambling is observed. The active form of the catalyst is produced only in the presence of the starting material. Kinetic experiments, especially those concerning the introduction periods and the inhibition, are indicative of a complex reaction mechanism. The first hydrogen is preferentially abstracted from the 2-position, the second with complete cis selectivity.
    Notes: Der aus Ni(acac)2 und AlEt3 dargestellte Katalysator zeigt eine hohe Aktivität beim H-Transfer zwischen Dihydroarenen, neben dem Isomerisierungen und H/D-Austausch kaum ablaufen. Die aktive Form entsteht erst in Gegenwart des Edukts. Kinetische Untersuchungen, vor allem zur Induktionsperiode und zur Hemmung, deuten auf einen komplexen Ablauf. Der Wasserstoff wird cis-selektiv abgespalten, primär bevorzugt aus der 2-Position.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1925-1927 
    ISSN: 0009-2940
    Keywords: Hydrogen transfer ; Olefin isomerization ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrogen Transfer Reactions, 13.  -  Catalysis of Disproportionation by (Dinitrogen)hydridotris(triphenylphosphine)cobalt(I)For both C—H activation and olefin isomerization, CoH(N2)(PPh3)3 (1) is a more powerful catalyst than the Wilkinson complex. In 1,2-dihydronaphthalene (2), a two-step cis abstraction of the hydrogen atoms is found with small regioselectivity in the first step.
    Notes: Die Aktivität des Komplexes CoH(N2)(PPh3)3 (1) liegt bei der C—H-Aktivierung deutlich höher als beim Wilkinson-Katalysator. Noch effektiver wird aber eine Olefin-Isomerisierung induziert. Die zweistufige H-Abstraktion erfolgt beim 1,2-Dihydronaphthalin (2) cis-selektiv, der Primärschritt aber kaum regioselektiv.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1935-1938 
    ISSN: 0009-2940
    Keywords: as-Triazinium salt, fused ; Ring transformation ; Solvatochromy, negative ; Zwitterion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Ringtransformation von neuen kondensierten as-Triazinium-SalzenDie Reaktion des 1,2-Diaminopyridinium-Salzes 1 mit dem Furandion 2 ergab ein Pyrido-as-triazinon 3, das zum tricyclischen Furo[2,3-e]pyrido[1,2-b]-as-triazinium-Salz 5 cyclisiert wurde. Die Reaktion von 5 mit Nucleophilen führte zu unterschiedlichen Produkten: mit wäßriger Base entstand das bicyclische Triazinon 4, mit dem Methoxid-Ion und sekundären Aminen wurden die stabilen Zwitter-Ionen 7a, b erhalten, wohingegen Ammoniak und Hydrazine unter Transformation des Furanringes die neuen tricyclischen kondensierten Pyrrole 10, 11 bzw. Pyridazine 13, 14a, b ergaben.
    Notes: The 1,2-Diaminopyridinium salt 1 was treated with furandione 2 to give pyrido-as-triazinone 3, which could be cyclized to the tricyclic furo[2,3-e]pyrido[1,2,-b]-as-triazinium salt 5. Reaction of 5 with nucleophiles resulted in different types of products. Thus, aqueous base afforded bicyclic triazinone 4, methoxide ion or secondary amine led to stable zwitterions 7a, b, whereas ammonia and hydrazines resulted in ring transformation of the furan moiety, and gave new fused tricyclic pyrroles (10, 11) and pyridazines (13, 14), respectively.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1947-1953 
    ISSN: 0009-2940
    Keywords: Enol ethers ; [n](2,4)Phloroglucinophanes ; Autoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations of the Autoxidation and the Rearrangement of [n](2,4)PhloroglucinophanesIn the autoxidation of [n](2,4)phloroglucinophanes 3 hydroperoxides 7 are isolated in several cases as the first oxidation products; they react to the more stable monohydroxylated compounds 8 with different rates. Acylphloroglucinophanes 5, however, react with oxygen to give the dihydroxylated compounds 9. The autoxidation rate of the phloroglucinophanes 3, 5 is markedly larger than that of diethylphloroglucinols 6. In alkaline solution the hydroxy compounds 8 rearrange to the dihydroxycyclopentenones 12; the rate of rearrangement correlates with the decrease of ring strain.
    Notes: Bei der Autoxidation von [n](2,4)Pholoroglucinophanen 3 können in einigen Fällen Hydroperoxide 7 als erste Oxidationsprodukte isoliert werden, die unterschiedlich rasch in die stabileren monohydroxylierten Verbindungen 8 übergehen. Aclphloroglucinophane 5 reagieren mit Luftsauerstoff dagegen zu den zweifach hydroxylierten Verbindungen 9. Die Geschwindigkeit der Autoxidation ist bei den Phloroglucinophanen 3, 5 deutlich größer als bei den 2,4-Diethylphloroglucinen 6. Im alkalischen Medium lagern sich die Hydroxyverbindungen 8 in die Dihydroxycyclopentenone 12 um, wobei für die Geschwindigkeit der Umlagerung eine Korrelation mit der Abnahme an Ringspannung gefunden wird.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1963-1967 
    ISSN: 0009-2940
    Keywords: Allenyl azides, ring closure of ; Propargyl azides, rearrangement, base-induced ; Triazafulvenes, nucleophilic addition to ; 1,2,3-Triazoles, preparation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Unsaturated Azides, 7.  -  Base-catalyzed Formation of Allenyl Azides from Propargyl Azides: New Syntheses for 1,2,3-TriazolesThe propargyl azides 10, 14, 17, 20, and 28 undergo a base-catalyzed (prototropic) rearrangement to short-lived allenyl azides. These intermediates rapidly cyclize to triazafulvenes, which can be trapped by nucleophiles (methanol, sodium hydroxide, ammonia) to give 1,2,3-triazoles. Starting with the precursors 9, 13, 16, 19, and 27 one-pot syntheses lead to the heterocycles 12, 15, 18, 21, and 29. Depending on the reaction conditions, compound 10 regioselectively yields 12c (75%) by prototropic rearrangement (path B) or by migration of the azide group (path A) the isomer 11c (62%).
    Notes: Die Propargylazide 10, 14, 17, 20 und 28 lagern sich basenkatalysiert (prototrop) zu kurzlebigen Allenylaziden um. Diese Zwischenstufen cyclisieren rasch zu Triazafulvenen, die mit Nucleophilen (Methanol, Natriumhydroxid, Ammoniak) als 1,2,3-Triazole abgefangen werden können. Ausgehend von den Vorläufern 9, 13, 16, 19 und 27 führen Eintopf-Synthesen zu den Heterocyclen 12, 15, 18, 21 und 29. In Abhängigkeit von den Reaktionsbedingungen liefert 10 über die prototrope Umlagerung (Weg B) regioselektiv 12c (75%) oder durch Azidwanderung (Weg A) die isomere Verbindung 11c (62%).
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2023-2025 
    ISSN: 0009-2940
    Keywords: Homoallylic alcohols ; [2,3] Sigmatropic rearrangement ; Stereoselective synthesis of alcohols ; [2,3] Wittig rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reductive cleavages of allyl [(phenylthio)methyl] ethers (8, 11) and an allyl [(tolylsulfonyl)methyl] ether (14) with lithium naphthalenide in THF furnish homoallylic alcohols (9, 12). The steric course of these transformations (E/Z selectivity in the case of 9, syn/anti selectivity for 12) is very similar to that of analogous Wittig-Still rearrangements.
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2049-2054 
    ISSN: 0009-2940
    Keywords: Ligating properties ; Pentaphosphaferrocenes ; Sandwich and triple-decker complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pentaphospaferrocenes as Complex LigandsThe interaction of [Cp*Fe(P5)] (1a) with [Cr(CO)5(thf)] and [Cp(CO)2Mn(thf)], respectively, affords [Cp*Fe(P5){Cr(CO)5}2] (2) as well as [Cp*Fe(P5){Mn(CO)2Cp}n] (4a-d; n = 1-4; Cp* = η5-C5Me5). Irradiation of 1 and [CpFe(C6H6)]PF6 gives the cationic 30-VE triple-decker complexes [CpFe(μ, η5-P5)Fe(C5Me4R)]PF6 (3a: R = CH3; 3b: R = C2H5; Cp = η5-C5H5). In addition to the NMR studies 2 and 3b have been characterized by X-ray structure analyses.
    Notes: Die Umsetzung von [Cp*Fe(P5)] (1a) mit [Cr(CO)5(THF)] bzw. [Cp(CO)2Mn(THF)] ergibt [Cp*Fe(P5){Cr(CO)5}2] (2) sowie [HCp*Fe(P5){Mn(CO)2Cp}n] (4a-d; 1-4; Cp* = η5-C5Me5). Aus 1 und [CpFe(C6H6)]PF6 lassen sich photochemisch die kationischen 30-VE-Tripeldeckerkomplexe [CpFe(μ, η5-P5)Fe(C5Me4R)]PF6 (3a: R = CH3; 3b: R = C2H5; Cp = η5-C5H5) aufbauen. Zusätzlich zu den NMR-spektroskopischen Studien wurden von 2 und 3b Kristallstrukturanalysen angefertigt.
    Additional Material: 3 Ill.
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  • 78
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    Berichte der deutschen chemischen Gesellschaft 122 (1989) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 79
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1139-1145 
    ISSN: 0009-2940
    Keywords: C-(Alkylideneamino)ketene imines ; Isocyanides, C=C coupling with aminocarbene ligands ; (2-Azaallenyl)chromium complexes ; 2-Imidazolin-5-ones ; α-Amino acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Syntheses via Transition Metal Complexes, 35. - (C-Amino) Ketene Imines, 2-Imidazolin-5-ones, and α-Amino Acids from Aminocarbene Chromium Complexes and IsocyanidesC-(Alkylidenamino)ketene imines 1,4-diaza-1,2,4-pentatrienes) 8 are easily accessible by C=C coupling of isocyanides R1 - NC (2, R1 = t-C4H9, c-C5H11, CH3) with the (alkylideneamino)carbene (= 2-azaallenyl-) ligand of (6). The tendency for an insertion of 2 into M=C bonds of aminocarbene complexes strongly depends on the electronic character of the aminocarbene ligand. Electron-rich aminocarbene chromium complexes like (CO)5Cr=C(NR2)C6H5 (1, R = H, CH3), show only little tendency for an insertion but mainly give cis-(R1-NC)(CO)4Cr=C(NR2C6H5 (3) by substitution of CO. Electron-poor aminocarbene complexes like 6 (readily available on N-benzoylation of 1a) undergo a facile insertion of 2 into the M=C bond with smooth formation of 7. From 7 ketene imine 8 is spontaneously disengaged by a second equivalent of 2. The reaction works especially well with bulky isocyanides 2a, b. In the case of methyl isocyanide (2c) a [bis(imino)dihydropyrrol]chromium complex 15 is obtained as a minor product besides 8c. 15 results from a [4+1] cycloaddition of 2c at the ketene imine ligand of 7c. C-(Alkylideneamino)ketene imines 8 are easily accessible by our method. They prove to be very thermolabile in solution and spontaneously isomerize to give 2-imidazolin-5-ones 10 and C-amidoketene imines 11. Under the influence of wet silica gel keten imine derivatives 8 rapidly form α-amino acid amides 16 by hydrolysis with concomitant migration of a benzoyl group. Under the same conditions 11 also gives the „normal“ α-amino acid amides 17.
    Notes: C-(Alkylideneamino)ketenimine (1,4-Diaza-1,2,4-pentatriene) 8 wurden durch C=C-Kupplung von Isocyaniden R1-NC (2, R1 = t-C4H9, c-C5H11, CH3) mit dem (Alkylideneamino)carben-(= 2-Azaallenyl-)Ligand von (6) erstmals hergestellt. Die Bereitschaft zur Insertion von 2 in M=C-Bindungen von Aminocarbenkomplexen hängt stark von den elektronischen Eigenschaften der Aminocarbenliganden ab. Elektronenreiche (Aminocarben)chromkomplexe, wie z. B. (CO)5Cr=C(NR2)C6H5 (1, R = H, CH3), zeigen eine nur geringe Neigung zur Insertion von 2 und bilden bevorzugt cis-(R1-NC)(CO)4Cr=C(NR2C6H5 (3) unter Substitution von CO. Elektronenarme (Aminocarben)chromkomplexe hingegen, wie z. B. 6 (durch N-Benzoylierung von 1a leicht zugänglich), zeigen ausschließlich Insertion zu 7. Aus 7 wird spontan 8 freigesetzt durch Substitution mit einem zweiten Äquivalent 2. Sperrige Isocyanide 2a, c reagieren besonders einheitlich. Mit Methylisocyanid (2c) entsteht zusätzlich zu 8c der [Bis(imino)dihydropyrrol]-chromkomplex 15 unter [4+1]-Cycloaddition von 2c am Keteniminligand von 7c. C-(Alkylidenamino)ketenimine 8 sind nach unserem Verfahren einfach zugänglich; sie isomerisieren jedoch leicht zu 2-Imidazolin-5-onen 10 und C-Amidoketeniminen 11. An feuchtem Kieselgel entstehen aus 8 rasch α-Aminosäureamide 16 durch Hydrolyse unter Wanderung eines Benzoylrestes; aus 11 unter gleichen Bedingungen zusätzlich „normale“ α-Aminosäureamide 17.
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  • 80
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2177-2181 
    ISSN: 0009-2940
    Keywords: Benzonitriles ; Hetero Diels-Alder reactions, “inverse” ; Pyrazines, annulated ; Triazines, benzofuro- and benzothieno- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Donor-Substituted Benzoitriles as Side-Chain Dienophiles in the Intramolecular [4+2] Cycloaddition with Inverse Electron DemandExpanding the scope of the intramolecular Diels-Alder reaction of 1,2,4,5-tetrazines to include donor-substituted benzonitriles as side-chain dienophiles we describe synthetic routes to novel fused heterotricycles such as the benzofuro[3,2-e]-1,2,4-triazines 11a, b and the benzothieno[3,2-e]-1,2,4-triazines 14a, b, and 17. The doubly annulated pyrazines 22 and 23 are constructed by a subsequent second intramolecular Diels-Alder cycloaddition of the benzonitrile moiety with the fused 1,2,4-triazine system, starting from 11a and 14a.
    Notes: Unter Einschluß donorsubstituierter Benzonitrile als Seitenkettendienophile haben wir die Anwendungsbreite der intramolekularen Diels-Alder-Reaktion von 1,2,4,5-Tetrazinen erweitert und beschreiben Synthesewege zu neuen anellierten Heterotricyclen wie den Benzofuro[3,2-e]-1,2,4-triazinen 11a, b und den Benzothieno[3,2-e]-1,2,4-triazinen 14a, b sowie 17. Die doppelt anellierten Pyrazine 22 und 23 lassen sich durch eine nachfolgende zweite intramolekulare Benzonitril/1,2,4-Triazin-Diels-Alder-Cycloaddition mit 11a bzw. 14a als Edukten herstellen.
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  • 81
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2147-2157 
    ISSN: 0009-2940
    Keywords: 1,3-Dipolar cycloadditions, intramolecular ; Nitrile oxides ; Regioselectivity ; Furanophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Intramolecular Cycloadditions with Nitrile Oxides: Investigtions towards the Synthesis of HeterophanesThe intramolecular cycloaddition reactions of the nitrile oxides 30a-d, 35, 36, and 47, obtained in situ from the 2,5-difunctional furan hydroximoyl chlorides 12a, b, 18 and the nitro compounds 9c, d, 21, 29, are described. With 30c the expected isoxazolofuranophane of type 31 is formed in acceptable yield; the additionally formed regioisomer 32c and the dimer 34c are very minor products in this case. Whereas the highest homologue 30d gives a complex product mixture with small amounts of 31 d and the macrocycle 34d as the only identified compounds, the derivatives bearing a shorter side chain (30a, b; n = 1, 2) give rise to the exclusive reaction of the dipole with a double bond of the furan system (to give 33a, b). The same behavior is observed in the case of the electronically and sterically modified dipole systems 35/36 and 47, resp.; in spite of the much more favorable conditions for the formation of cyclophanes the cycloadditions result in the exclusive formation of the heterotricycles 41, 42 and 49. Possible preparative applications of the isomeric cycloaddition compounds are discussed.
    Notes: Die intramolekularen Cycloadditionsreaktionen der aus 2,5-difunktionellen Furan-Hydroximsäurechloriden (12a, b und 18) bzw. den Nitroverbindungen 9c, d, 21 und 29 in situ hergestellten Nitriloxide 30a-d, 35, 36 und 47 werden beschrieben. Eine Reaktion zu den angestrebten Isoxazolo-furanophanen des Typs 31 verläuft für 30c in brauchbarer Ausbeute; das Regioisomere 32c sowie das Dimere 34c treten hierbei nur in geringem Maße auf. Während das höchste Homologe 30d neben 31d und dem Makrocyclus 34d hauptsächlich Zersetzungsprodukte bildet, reagieren die Derivate mit kürzerer Seitenkette (30a, b; n = 1, 2) ausschließlich unter dipolarer Addition an eine Furandoppelbindung zu 33a, b. Für n = 1 entsprechen diesem Verhalten auch die elektronisch bzw. sterisch modifizierten Dipolsysteme 35/36 und 47, die trotz günstigerer Voraussetzungen für die Cyclophanbildung nur zu den Tricyclen 41, 42 bzw. 49 reagieren. Die präparativen Anwendungsmöglichkeiten der isomeren Cycloadditionsverbindungen als Synthesezwischenprodukte werden diskutiert.
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  • 82
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2183-2185 
    ISSN: 0009-2940
    Keywords: [4 + 2] Cycloaddition ; 3,5-Dihydroxytropone ; Singlet oxygen ; Y aromaticity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von 3,5-DihydroxytroponWir beschreiben eine vierstufige Synthese des bisher unbekannten 3,5-Dihydroxytropons (6), die von Tropon ausgeht und eine [4 + 2]-Cycloaddition mit Singulett-Sauerstoff einschließt.
    Notes: Starting from tropone, the hitherto unknown 3,5-dihydroxytropone (6) is prepared in a four-step synthesis including a [4 + 2] cycloaddition reaction of singlet oxygen.
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  • 83
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2207-2208 
    ISSN: 0009-2940
    Keywords: Allenes ; Hetero Diels-Alder reactions ; Catalysis, heterogeneous ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some examples of cycloadditions of 1-ethoxy-1,2-propadiene with 1-oxa-1,3-dienes, catalyzed by acid-free silica gel, are reported.
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  • 84
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    Berichte der deutschen chemischen Gesellschaft 122 (1989) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 85
    ISSN: 0009-2940
    Keywords: Bisporphyrinates, cerium(IV) ; Lanthanoid porphyrins ; Metalloporphyrins ; Tetrapyrrole complexes, sandwich-like ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metallkomplexe mit Tetrapyrrol-Liganden, LIV.  -  Synthese, Spektren, Struktur und Redox-Chemie von Cer(VI)-Bisporphyrinaten mit gleichen und verschiedenen Porphyrin-Ringen im Sandwich-SystemWeitere symmetrische Cer(IV)-Bisporphyrinate werden aus Cer-(III)-acetylacetonat und Tetraphenylporphyrin, Tetra-p-chlorphenylporphyrin, und Hexadecahydrotetrabenzporphyrin hergestellt. Aus dem letzteren Porphyrin entsteht auch ein Biscer(III)-Tripeldecker; ein solcher bildet sich als einziges Produkt aus Octamethylporphyrin. Aus einem Gemisch zweier verschiedener Porphyrine, nämlich Octaethylporphyrin [H2(OEP)], und Tetraphenyl-porphyrin [H2(TPP)] oder Tetra-p-chlorphenylporphyrin [H2-(TClP)] erhält man neben den symmetrischen Spezies Ce(OEP)2 und Ce(TPP)2 die unsymmetrischen („gemischten“) Doppeldecker Ce(OEP)(TPP) oder Ce(OEP)(TClP), die verschiedene Porphyrin-Ringe im Sandwich-System haben und sich trennen lassen. Die Kristallstrukturanalyse von Ce(OEP)(TPP) zeigt CeIV in quadratisch-antiprismatischer Umgebung der Pyrrol-N-Atome der Porphyrin-Ringe. Während die IR- und NMR-Spektren der unsymmetrischen Doppeldecker-Überlagerungen der Spektren, die einzelnen Ringe darstellen, zeigen ihre UV/VIS-Spektren und die cyclischen Voltammogramme, daß die zwei unterschiedlichen Porphyrin-Ringe sich wie ein gemeinsames π-Elektronensystem verhalten. Die Darstellung der π-Kation-Radikal-Salze [Ce(OEP)2]-ClO4 und [Ce(OEP)(TPP)]SbCl6 wird ebenfalls beschrieben. In letzterem scheint sich das Defektelektron bevorzugt im OEP-Ring aufzuhalten.
    Notes: Further symmetrical cerium(IV) bisporphyrinates are prepared from cerium(III) acetylacetonate and tetraphenylporphyrin, tetra-p-chlorophenylporphyrin, and hexadecahydrotetrabenzporphyrin. In the latter case, a biscerium(III) triple-decker is also found which is the only product in the case of octamethylporphyrin. From a mixture of two different porphyrins, namely octaethylporphyrin [H2(OEP)] and either tetraphenylporphyrin [H2(TPP)] or tetra-p-chlorophenylporphyrin [H2(TClP)], besides the symmetrical species Ce(OEP)2 and Ce(TPP)2, the unsymmetrical (“mixed”) double-deckers Ce(OEP)(TPP) or Ce(OEP)(TClP) are obtained which have different porphyrin rings in the sandwich system and can be separated by chromatography. The crystal structure analysis of Ce(OEP)(TPP) shows CeIV in a square-antiprismatic geometry of the pyrrole N atoms of the porphyrin rings. While the IR and NMR spectra of the unsymmetrical double-deckers are superpositions of the spectra of the individual rings, their UV/VIS spectra and cyclic voltammograms indicate that the two porphyrin rings behave as a common π-electron system. The preparation of the π-cation radical salts [Ce(OEP)2]ClO4 and [Ce(OEP)(TPP)]SbCl6 is also described. In the latter, the defect electron seems to reside preferentially in the OEP ring.
    Additional Material: 5 Ill.
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  • 86
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2261-2264 
    ISSN: 0009-2940
    Keywords: Iron, thiocarbonyl complex ; Iron-tin bond ; NMR, 13C-, 17O-, and 119Sn ; Dynamic molecules ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Fe-Sn Bonds by the Reaction of Tris(trimethylstannyl)amine with Fe(CO)5 and Fe(CO)4CS; 13C-, 17O-, and 119Sn-NMR-Spectroscopic StudiesThe reaction between N(SnMe3)3 and Fe(CO)5 gives the known complex cis-Fe(CO)4(SnMe3)2 (1) in high yield. In the analogous reaction of Fe(CO)4CS the complex fac-Fe(CO)3(CS)(SnMe3)2 (2) is obtained together with small amounts of 1. In addition to the 13C-NMR data, the 17O- and 119Sn-NMR measurements proved particularly useful for studying the dynamic behaviour of 1 and 2.
    Additional Material: 3 Ill.
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2273-2274 
    ISSN: 0009-2940
    Keywords: Fluorine, application in organometallic chemistry ; Rhenocene(V)-trichloride ; Rhenocene(VII)-dichloride trication ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dichlorobis(η5-cyclopentadienyl)rhenium(VII) Tris(hexafluoroantimonate): Synthesis of the First Rhenocene(VII) Dichloride CationRhenocene trichloride ([Cp2ReCl2]⊕ Cl⊖, 1) reacts with one equivalent of AgSbF6 and three equivalents of SbF5 to provide [Cp2ReCl2]3⊕[SbF6]⊖3 (2) in high yield. 2 contains the first rhenocene(VII) dichloride cation and is the first member of a 16-electron group-7 species of the type [Cp2MCl2]n⊕ [EF6]n⊖ (M = Ti, Zr, Hf: n = 0; M = V, Nb: n = 1; M = Mo, W: n = 2; M = Re: n = 3; E = As, Sb).
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  • 88
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Thiophosphinito complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXVII.  -  Stereochemical Impacts on the Transition of Monomeric Thiophosphinito Manganese Compounds to the Dimeric Complexes The η2-thiophosphinito manganese complexes (3d, e) and the dimeric complexes (4a-c, f) are obtained from BrMn(CO)5 (1) and the secondary phosphane sulfides R2P(S)H (2a-f) [R = Me (a), Et (b), n-Pr (c), i-Pr (d), Cy (e), Ph (f)] in the presence of the auxiliary base Et(i-Pr)2N with elimination of CO. For the kinetic stabilization of 3d, e sterically demanding substituents R at the phosphorus are suitable. The Mn—S bond in 3e is easily cleaved under CO pressure (100 bar) resulting in the formation of (5e). The reaction 3e ⇆ 5e is reversible.
    Additional Material: 1 Tab.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2283-2287 
    ISSN: 0009-2940
    Keywords: Indium, trialkyl derivatives ; Dialkylchloroindium ; Alkyldichloroindium ; Alkylindium dialkylamides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of iPr2InCl, iPrInCl2, and (iPr2InHRtBu)2The reactions of triisopropylindium (1) with half an equivalent or two equivalents of indium (III) chloride leads to iPr2InCl (2) and iPrInCl2 (3), respectively. (iPr2InNHtBu)2 (4) can be synthesized from 2 and LiNHtBu. According to NMR, IR, and RE studies, 2-4 from dimers in solution and solid state. The X-ray analysis of 4 is reported.
    Additional Material: 2 Ill.
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  • 90
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2311-2317 
    ISSN: 0009-2940
    Keywords: Allenes, 1,3-diamino- and 1-amino-3-thio- ; Propene iminium salts ; Propyne iminium salts ; MO calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Propyne Iminium Salts: Ambifunctional reactivity reactivity towards Sulfur and Nitrogen NucleophilesPropyne iminium ions 2a-d have been studied by both ab initio (3-21G//3-21G for 2a) and MNDO calculations (2a-d). It is found that the amino group stabilizes the propargyl cation structure at the expense of the allenyl cation structure. Furthermore, the highest positive charge density is located at the amino-substituted carbon atom.  -  Reactions of 2-propyne iminium triflates 6a, b with thiols, thiolates, morpholine, lithium morpholide, and phenylhydrazine have been investigated. C-1 attack at 6, expected under kinetically controlled conditions, is observed in a few cases only. In all other cases, products resulting from C-3 attack takes place leading either to 1,3-donorsubstituted allenes (8, 10, 12) in the absence of proton sources or to their C-2-protonated forms (9, 11, 13-15) otherwise.
    Notes: Für die Propiniminium-Ionen 2a-d werden ab-initio- (3-21G//3-21G für 2a) und MNDO-Rechnungen (2a-d) durchgeführt. Danach stabilisiert die Aminogruppe die Propargylkation- eindeutig gegenüber der Allenylkation-Struktur. Die höchste positive Ladungsdichte befindet sich am aminosubstituierten Kohlenstoffatom.  -  Umsetzungen der 2-Propiniminium-triflate 6a, b mit Thiolen, Thiolaten, Morpholin, Lithium-morpholid und Phenylhydrazin zeigen, daß nur in einigen Fällen unter kinetisch kontrollierten Bedingungen der erwartete C-1-Angriff erfolgt, ansonsten wird C-3-Angriff gefunden. Letzterer führt in Abwesenheit von Protonquellen zu 1,3-donorsubstituierten Allenen (8, 10, 12), andernfalls entstehen deren C-2-protonierte Formen (9, 11, 13-15).
    Additional Material: 3 Tab.
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  • 91
    ISSN: 0009-2940
    Keywords: Diels-Alder reactions, intramolecular ; Allenecarboxyamides, N-(hetarylmethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloadditons, 17.  -  Influence of Methyl and Phenyl Groups in the Allenic ω-Position on the Thermally Induced Isomerizations of N-[2-Furanyl-(Thienyl-, Pyrrolyl-)methyl] allenecaboxamindesThe N-(2-hetarylmethyl)-1,2-alkadienecarboxamides 9a-q were synthesized by the ylide route, and their readiness to participate in the intramolecular Diels-Alder reaction was studied. Whereas the pyrrole derivatives 9p and 9q and the thiophene derivative 9o without directly bonded phenyl nuclei only decompose, the thiophene allenes 9m and 9n form the “normal” tricycles 12a and 12b by reaction of their amide phenyl nucleus (R1 = Ph). In all N-furfurylallenecarboxamides 9a-1 the furan nucleus is involved in the intramolecular Diels-Alder reaction, irrespective of the amine substituent R1. The furan nucleus reacts in all cases with the terminal allenic double bond to form the oxatricycles 10a-1 containing a six-membered lactam moiety. Reaction with the first allenic double bond (formation of 11c, d, and g) only takes place, when the reaction with the other double bond is slowed down by one or two methyl groups in the ω-position and the formation of 11 is not prevented by a methyl group in the furan 5-position.
    Notes: Die N-(2-Heteroarylmethyl)-1,2-alkadiencarboxamide 9a-q werden auf dem Ylid-Weg synthetisiert und auf ihre Bereitschaft zur intramolekularen Diels-Alder-Reaktion untersucht. Die Pyrrolderivate 9p und 9q und das Thiophen-Derivat 9o ohne direkt gebundenen Phenylkern zeigen lediglich Zersetzung, während die Thiophen-Allene 9m und 9n durch Reaktion ihrer Amid-Phenylkerne (R1 = Ph) die „normalen“ Tricyclen 12a und 12b bilden. In allen Furfuryl-allencarboxamiden (9a-1) geht der Furankern die intramolekulare Diels-Alder-Reaktion ein, unabhängig von der Art des Aminsubstituenten R1. Der Furankern reagiert in allen Fällen mit der endständigen Doppelbindung zu den Oxatricyclen 10a-1 mit sechsgliedrigem Lactamteil. Reaktion mit der ersten allenischen Doppelbindung (s. Bildung von 11c,d und g) wird daneben nur beobachtet, wenn durch Einbau von Methyl-gruppen in die ω-Position die Reaktion mit der endständigen Doppelbindung stark verlangsamt und die Bildung von 11 nicht durch eine Methylgruppe in der Furan-5-Position verhindert wird.
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  • 92
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2377-2389 
    ISSN: 0009-2940
    Keywords: EPC syntheses ; Δ4-1,3-Oxazoline, derivatives ; Simmons-Smith reaction ; Sakurai reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloadditions to the Double Bond of Methyl (R)-2-tert-Butyl-Δs4-1,3-oxazoline-3-carboxylates1The title compounds (with or without an additional substituent, such as methyl or vinyl, in the 5-position) are allowed to react with peracids (→ dihydroxy derivatives 3), with cyclopropanation reagents (such as ICH2ZnEt, N2CHCOOEt, HCBr3, or HCCl3/NaOH → products 5-9), with tetracyanoethylene and OsO4 (see four- and five-membered rings in 19, 20), with dienophiles (maleic anhydride, see 23). The double bond of the oxazolines reacts in a highly diastereoselective manner, with the attack preferred from the face of the five-membered ring remote from the tert-butyl group. Some of the products obtained undergo or are subjected to further reactions (4, 12-18, 23, 29-33). Stereochemical and synthetic aspects of the reactions are discussed.
    Notes: Die Titelverbindungen (mit und ohne zusätzliche Substituenten wie z. B. Methyl oder Vinyl in der 5-Stellung) werden mit Persäuren (→ Dihydroxyderivate 3), mit Cyclopropanierungsreagentien (wie z.B. ICH2ZnEt, N2CHCOOEt, HCBr3 oder HCCl3/NaOH → Produkte 5-9), mit Tetracyanethylen und OsO4 (→ Produkte 19-20) und mit Dienophilen (Maleinsäureanhydrid, siehe 23) umgesetzt. Die Doppelbindung der Oxazoline reagiert hoch diastereoselektiv, wobei der bevorzugte Angriff von der der tert-Butylgruppe abgewandten Seite erfolgt. Einige der erhaltenen Produkte werden weiter umgesetzt (siehe 4, 12-18, 23, 29-33). Stereochemische und synthetische Aspekte der Reaktionen werden diskutiert.
    Additional Material: 2 Ill.
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2397-2398 
    ISSN: 0009-2940
    Keywords: Nucleophilic ring opening ; Regioselectivity ; Ambident nucleophiles ; Aziridines ; Tryptamine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions with Aziridines, 52.  -  branched-Chain Tryptamine Compounds from Indolyllithium and Activated AziridinesReaction of indolyllithium 1 with activated aziridines 2 in toluene provides the tryptamines 3 or 4 in good yields.
    Additional Material: 1 Tab.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2407-2409 
    ISSN: 0009-2940
    Keywords: Organoantimony halides ; Aziridines, cycloaddition of, α-cleavage of ; Heterocumulenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of catalytic amounts of organoantimony(V) halides such as Ph4SbI, Ph4SbBr, Ph3SbBr2, and Ph3SbCl2, the cycloaddition of aziridines 1a-g with heterocumulenes (phenyl isothiocyanate, carbon disulfide, and carbon dioxide) selectively gave ring-expanded cycloadducts 3a-d, f, g, and 6e by α-cleavage of the aziridine rings.
    Additional Material: 2 Tab.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1263-1275 
    ISSN: 0009-2940
    Keywords: Rotational barriers ; Olefins, strained ; Heat of hydrogenation ; Force-field calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rotational Barriers of Strained OlefinesFor the olefins 1-8 heats of formation have been derived from heats of hydrogenation and force-field calculations, respectively. From the kinetics of their geometrical isomerisation the corresponding values for the transition states were obtained. The rotational barriers, which vary by nearly 30 kcal/mol, can be described by a unique torsional potential (65.9 ± 0.9 kcal/mol), which is independent of the degree of substitution, if a correction is made for the steric energy contribution in the ground- and transition-states.
    Notes: Für die Olefine 1-8 wurde durch Hydrierwärme-Messung bzw. Kraftfeld-Rechnung die Bildungsenthalpie der Grundzustände und durch kinetische Analyse der geometrischen Isomerisierung die der Übergangszustände ermittelt. Die um fast 30 kcal/mol variierenden Rotationsenthalpien lassen sich mit einer einheitlichen, vom Substitutionsgrad unabhängigen Torsionsbarriere (65.9 ± 0.9 kcal/mol) beschreiben, wenn um die sterischen Energiebeiträge der Grund- und Übergangszustand korrigiert wird.
    Additional Material: 5 Ill.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1285-1290 
    ISSN: 0009-2940
    Keywords: 2-Cyclopropylidene-1,3-diones ; Hetero Diels-Alder reaction ; Cyclopropane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [4+2] Cycloaddition reactions of 2-Cyclopropylidene-1,3-diones with Electron-Rich AlkynesCyclopropylidenedimedone 3, an unstable and highly reactive intermediate, is trapped in a Hetero Diels-Alder reaction by the addition of ynamines 7a-c, f, ynether 7d, or phenylacetylene (7e). Hydrolysis of the resulting cycloadducts 8a-d, f leads to carboxylic acid derivatives 9a-d, f. The latter may be regarded as the result of a twofold nucleophilic substitution at a cyclopropane system according to their synthesis by the sequence 17 → 5 → 8 → 9. An opening of the cyclopropane ring takes place during hydrolysis of cycloadduct 8e producing 11. Analogously, 2-cyclopropylidene-1,3-diones 13A-13C can be generated by aminocyclopropylation of CH acids 18A-18C and subsequent deamination induced by an acylation reaction. Trapping of 13A-13C by ethoxyacetylene (7d) or ethyl vinyl ether (4) provides the analogous cycloadducts 14A, B and 15C.
    Notes: Cyclopropylidendimedon 3, eine unbeständige und hochreaktive Zwischenstufe, kann durch Inamine 7a-c, f, Inether 7d oder Phenylacetylen (7e) in einer Hetero-Diels-Alder-Reaktion abgefangen werden. Die resultierenden Cycloaddukte 8a-d, f sind zu Carbonsäurederivaten 9a-d, f hydrolysierbar, die entsprechend ihrer Herstellung über die Reaktionssequenz 17 → 5 → 8 → 9 als Produkte einer zweifachen nucleophilen Substitution am Cyclopropan anzusehen sind. Das Cycloaddukt 8e läßt sich dagegen nur unter Öffnung des Dreirings zu 11 hydrolysieren. Analog können die 2-Cyclopropyliden-1,3-dione 13A-13C durch Aminocyclopropylierung von CH-Säuren 18A-18C und anschließende Desaminierung erzeugt und unter Zusatz von Ethoxyacetylen (7d) oder Ethylvinylether (4) zu den Cycloaddukten 14A, 14B und 15C abgefangen werden.
    Additional Material: 2 Tab.
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  • 97
    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Cyclopropanes ; Dienophile reactivity ; MNDO calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diels-Alder Reactions with Diacceptor-Substituted Methylene-cyclopropanes - A New Aspect for the Twofold Nucleophilic Substitution at Cyclopropanes(Diacylmethylene)cyclopropanes 3, generated from aminocyclopropanes 1 or 2 and acetyl chloride as highly reactive intermediates, are trapped by dienes 9a-c yielding the Diels-Alder products 10. Regioisomers 10Ab and 10Ac were isolated exclusively from the interaction of 1A with pentadiene 9b and isoprene (9c), respectively. Cycloadditions with bicyclic methylenecyclopropanes 3A and 3B stereospecifically generated the 1α,6α,7β-isomers 10A and 10B. Starting from 10 the products 16, 19, and 20 are obtained by a degradation reaction of the Meldrum's acid moiety or by an oxidative ring cleavage of the cyclohexene unit. An X-ray structural analysis is reported for 10Ac. Using MNDO calculations the reactivity of various (diacylmethylene)cyclopropanes 3 as dienophiles has been studied.
    Notes: (Diacylmethylen)cyclopropane 3, die als hochreaktive Zwischenstufen aus den Aminocyclopropanderivaten 1 bzw. 2 in Gegenwart von Acetylchlorid erzeugt werden, reagieren mit Dienen 9a-c zu Diels-Alder-Produkten 10. Aus der Umsetzung von 1A mit Pentadien 9b bzw. Isopren (9c) werden ausschließlich die Regioisomeren 10Ab und 10Ac isoliert. Die Cycloadditionen an die bicyclischen Methylencyclopropane 3A und 3B verlaufen stereospezifisch zu 1α,6α,7β-Isomeren 10A und 10B. Aus 10 lassen sich durch Abbau der Meldrumsäure bzw. durch oxidative Ringöffnung des Cyclohexens die Folgeprodukte 16,19 und 20 herstellen. Von 10Ac wurde eine Kristallstrukturanalyse angefertigt. Die Dienophil-Reaktivität von verschiedenen (Diacylmethylen)cyclopropanen 3 wird mit MNDO-Rechnungen untersucht.
    Additional Material: 1 Ill.
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  • 98
    ISSN: 0009-2940
    Keywords: Nitriles ; Spiro compounds ; Propellanes ; Indan derivatives ; Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese with Nitriles, LXXXII1). - On spiro [indan-pyrans] and Indene-propellanes - Adducts of 2-(Diccyanomethylene)-1,3-indandione with 1,3-Dicarbonyl CompoundsThe reactivity of 2-(dicyanomethylene)-1,3-indandione (1) towards 1,3-dicarbonyl compounds depends strongly on the nature of the CH acidic component. While the reaction with dimedone yields a spiro[chromene-4,2′indan] (2), indene-propellanes (3) are formed with acetoacetic esters. Adducts of acetylacetone and benzoylacetic acid ethyl ester to 1 have been identified as spiro[indan-2,2′-pyrans] (4). The propellane structure 3 is proven by X-ray analysis. Adducts 6 of CH acidic components with 3-(dicyanomethylene)-2-indolones 5 are used for reference measurements.
    Notes: 2-(Dicyanmethylen)-1,3-indandion (1) zeigt gegenüber 1,3-Dicarbonylverbindungen ein überraschend differenziertes Reaktionsverhalten, das von der CH-aciden Komponente abhängt. Während mit Dimedon ein Spiro[chromen-4,2′-indan] (2) entsteht, führt die Reaktion mit Acetessigsäure-ethyl- bzw. -tert-butylester zur Bildung der Inden-propellane 3. Die Addukte von Acetylacaton und Benzoylessigsäure-ethylester an 1 erweisen sich als Spiro[indan-2,2′-pyrane] (4). Die Propellanstruktur 3 wird durch eine Röntgenkristallstrukturanalyse abgesichert. Addukte 6 CH-acider Komponenten an 3-(Dicyanmethylen)-2-indolone 5 werden für Vergleichsmessungen verwendet.
    Additional Material: 1 Ill.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1623-1627 
    ISSN: 0009-2940
    Keywords: Binuclear complexes ; Molybdenum complexes ; Rhodium complexes ; Sulfur dioxide bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sulfur(IV) Compounds as Ligands, IX.  -  Binuclear Molybdenum-Rhodium Complexes with Sulfur Dioxide as a Bridging LigandThe hetero-binuclear complexes [MoRhCl(CO)3(μ-SO2)(μ-Ph2E1CH2E3Ph2)(μ-Ph2E2CH2E4Ph2)] (E = P, As, 1-4), [MoRhBr(CO)3(μ-SO2)(μ-Ph2PCH2PPh2)2] (5) and [MoRh(CN)(CO)3(μ-SO2)(μ-Ph2PCH2PPh 2)2] (6) are the first compounds which contain sulfur dioxide as a bridging ligand connected to two metal atoms from different groups of the periodic table. The synthesis starts from Mo(CO)3(NCMe)3 (7), which reacts with the chelating ligands Ph2PCH2PPh2 (dppm), Ph2AsCH2PPh2 (dapm), and Ph2AsCH2AsPh2 (daam) to give the mononuclear precursors Mo(CO)3-(η2-Ph2E1CH2E3 Ph2)(η1-Ph2E2CH2E4 Ph2) (9-12). With [Rh2Cl2(CO)4] these are converted to the binuclear complexes [MoRhCl(CO)4(μ-Ph2E1CH2E3 Ph2)(μ-Ph2E2CH2E4Ph 2)] (15-18). Reversible CO/SO2 exchange finally gives 1-4 and the analogous bromide 5, the cyanide complex 6 is obtained from 1 and NaCN in liquid ammonia.
    Notes: Die heteronuklearen Zweikernkomplexe [MoRhCl(CO)3(μ-SO2)(μ-Ph2E1CH2E3Ph2)(μ-Ph2E2CH2E4Ph2)] (E = P, As, 1-4), [MoRhBr(CO)3(μ-SO2)(μ-Ph2PCH2PPh2)2] (5) und [MoRh(CN)(CO)3-(μ-SO2)(μ-Ph2PCH2PPh 2)2] (6) sind die ersten Verbindungen, in denen Schwefeldioxid als Brückenligand an zwei Metallatome aus verschiedenen Gruppen des Periodensystems gebunden ist. Die Synthese geht von Mo(CO)3(NCMe)3 (7) aus, das mit den Chelatliganden Ph2PCH2PPh2 (dppm), Ph2AsCH2PPh2 (dapm) und Ph2AsCH2AsPh2 (daam) zu den einkernigen Vorstufen Mo(CO)3(η2-Ph2E1CH2E3 Ph2) (η1-Ph2E2CH2E4 Ph2) (9-12) umgesetzt wird. Daraus entstehen mit [Rh2Cl2(CC)4] die Zweikernkomplexe [MoRhCl(CO)4(μ-Ph2E1CH2E3Ph 2)(μ-Ph2E2CH2E4Ph2)] (15-18). Reversibler CO/SO2-Austausch ergibt schließlich 1-4 und das analoge Bromid 5, der Cyanokomplexe 6 wird aus 1 und NaCN in flüssigem Ammoniak erhalten.
    Additional Material: 1 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1825-1850 
    ISSN: 0009-2940
    Keywords: Organoboranes, unsaturated ; Organosilanes, unsaturated ; Aminotriorganoborates ; Cyclization ; 2,5-Dihydro-organo-1,2,5-azasilaboroles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organosubstituted 2,5-Dihydro-1,2,5-azasilaboroles - Methods of Preparation and Spectroscopic CharacterisationThe compounds (E)-R22R2′ElIVC(R3) = C(R4)BR25 [(E)-1a to -g] are prepared from Na[R34,5BC ≡ CR3] with ClElIVR22R2′ [ElIV = Si, Ge, Sn] or from R22R2′SiC ≡ CR3 with BR34,5 (R4,5 = CH3, C6H5). The substituted silol 1z is obtained from (CH3)2Si(C ≡ CCH3)2 and B(C2H5)3, the mixture of (Z/E)-1t from (CH3)3SiC ≡ CH and B(C2H5)3. - ClSi(CH3)2C(CH3)2C(CH3)=C(C2H5)B(C2H5)Cl (C) reacts with LiN(CH3)2 to form (CH3)2NSi(CH3) 2C(CH3)2 C(CH3)=C(C2H5) B(C2H5)N(CH3)2 (E)-1n. - (E)-1a to (E)-1g or (E)-1a or (E)-1aGe and (E)-1aSn add MNH2 (M = Na, K) to yield the compounds MNH2-1, which react to the solid alkaline metal heterocycles M-2 after liberating R2H. From. (E)-1a or (E)-1b with LiNH2 the compounds (E)-C2H5CH=CR4Si(CH3)3 (A, B) are obtained. - On heating M-2a to M-2g eliminate R5H (C2H6) and smoothly from the solid compounds M-3, from which the heterocycles (4a-f) are prepared with CH3I. The 1-phenyl derivatives 5a, b are obtained from 4a,b with aniline. M-2c,d react with HCl to give the compounds 6c,d from which 7c,d are formed after C2H6 elimination. The 5-chloro compound 4i is used for the preparation of the heterocycles 4 with R5 = H, C(CH3)3, and N(CH3)2. - All compounds 1-7 are characterized by multinuclear NMR spectroscopy, the volatile compounds 1 and 4-7 also by their mass spectra.
    Notes: Die Verbindungen (E)-R22R2′ElIVC(R3) = C(R4)BR25 [(E)-1a bis -g] stellt man aus Na[34,5BC ≡ CR3] mit ClElIVR22R2′ [ElIV = Si, Ge, Sn] oder aus R22R2′SiC ≡ CR3 mit B34,5 (R4,5 = CH3, C6H5) her. Aus (CH3)2Si(C ≡ CCH3)2 und B(C2H5)3 sind das substituierte Silol 1z, aus (CH3)3)SiC ≡ CH und B(C2H5)3 im Autoklaven u. a. (Z/E)-1t zugänglich. - ClSi(CH3)2C(CH3) = C(C2H5)B(C2H5)Cl (C) und LiN(CH3)2 bilden (E)-1n. - (E)-1a bis (E)-1g bzw. (E)-1aGe und (E)-1aSn reagieren mit MNH2 (M = Na, K) zu den Additionsverbindungen MNH2-1, aus denen unter R2H-Abspaltung die festen Alkalimetall-Heterocyclen M-2 gebildet werden. (E)-1a und (E)-1b liefern mit LiNH2 (E)-C2H5CH=CR4Si(CH3)3 (A, B). - Aus M-2a bis M-2g erhält man beim Erhitzen unter R5H(C2H6)-Abspaltung glatt M-3, die mit CH3I zu den Heterocyclen (4a-f) reagieren. Die 1-Phenyl-Derivate 5a,b gewinnt man aus 4a,b mit Anilin. Aus M-2c,d sind mit HCl die Verbindungen 6c, d zugänglich, die unter C2H6-Abspaltung 7c,d liefern. Aus der 5-Chlor-Verbindung 4i stellt man die Heterocyclen 4 mit R5 = H, C(CH3)3 und N(CH3)2 her. - Sämtliche Verbindungen werden mit Multikern-NMR-Spektroskopie, die flüchtigen Verbindungen 1 und 4-7 auch massenspektrometrisch charakterisiert.
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