ZIB

1

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Plasma levels of thyrotropin-releasing-hormone in various splanchnic, renal, suprarenal, and cerebral veins (1987)

Vardarlı, İ. ; Wdowinski, J. M. ; Hoevels, J. ; [et al.]

Springer

Journal of molecular medicine 65 (1987), S. 134-137

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ISSN: 1432-1440

Keywords: TRH ; Brain ; Pancreas ; Human ; Plasma ; Selective blood sampling

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Endogenous TRH levels were determined in plasma obtained selectively via percutaneous transhepatic and femoral catheterization. TRH was measured using a very sensitive RIA method. In the pancreatic veins, internal jugular vein, left testicular vein, and other described veins, normal peripheral levels were found. An involvement of the TRH degrading enzyme (TDE) or a rapid intravasal dilution leading to normal peripheral TRH levels in the veins leaving the brain or pancreas, respectively, is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01728606

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2

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Effects of different compositions of diets and chronic ethanol administration on proteolytic and antiproteolytic systems in the pancreatic tissue of rats (1987)

Rämö, O. J. ; Jalovaara, P. ; Korhonen, L. K.

Springer

Research in experimental medicine 187 (1987), S. 95-103

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ISSN: 1433-8580

Keywords: Diet ; Ethanol ; Pancreas ; Proteolytic enzymes ; Protease inhibitors ; Liver ; Rat

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary The effects of dietary composition in combination with chronic ethanol ingestion on pancreatic proteolytic-antiproteolytic systems were studied by submitting 192 male Wistar rats to a 12-week dietary period. The rats were fed with a standard (S), fat-rich (F), protein-rich (P), or carbohydrate-rich (C) diet after randomized division into four groups. Half of the animals in each dietary group received water and the other half a mixture of 15% (v/v) ethanol and water as their drinking solution. The C-diet caused a significant increase of BAPNA hydrolysis, which was even more pronounced in rats receiving ethanol. Casein hydrolysis was increased significantly by the C-diet, but ethanol did not have any significant effect on this. Hydrolysis of ATEE was decreased significantly by the P- and C-diets, and ethanol in combination with the S- and F-diets decreased hydrolysis of ATEE in comparison with the corresponding water-receiving groups. The trypsin-inhibiting capacity of the pancreatic tissue was significantly increased in the group receiving C- and F-diets as compared to the S-diet-receiving group of animals. It seems that the composition of the consumed diet in combination with chronic ethanol ingestion may play a role in regulating the pancreatic proteolytic-antiproteolytic system. However, these changes were not parallel. The trypsin-inhibiting capacity of pancreatic tissue was also affected by the quality of the diet.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01851971

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3

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Aberrant expression of Class II major histocompatibility complex molecules by B cells and hyperexpression of Class I major histocompatibility complex molecules by insulin containing islets in Type 1 (insulin-dependent) diabetes mellitus (1987)

Foulis, A. K. ; Farquharson, M. A. ; Hardman, R.

Springer

Diabetologia 30 (1987), S. 333-343

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ISSN: 1432-0428

Keywords: Pancreas ; islets of Langerhans ; antigen-immune response ; autoimmunity ; Type 1 diabetes mellitus ; major histocompatibility complex

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Twenty-three patients with recent onset Type 1 (insulin-dependent) diabetes in whom residual insulin secreting B cells were present and 12 patients with disease of more prolonged duration (maximum 9 years), 8 of whom had residual B cells, were studied. Aberrant expression of Class II major histocompatibility complex molecules was demonstrated immunohistochemically on insulin secreting B cells in 21 out of 23 patients with recent onset disease and 6 of the patients with more prolonged disease. No such expression was seen on glucagon secreting A cells or somatostatin secreting D cells. Islets where there was marked hyperexpression of Class I major histocompatibility complex molecules on islet endocrine cells were seen in all cases in which residual B cells were present. Ninety-two per cent of insulin containing islets but only 1% of insulin deficient islets exhibited this phenomenon (p〈0.001, Chi-squared test). There was evidence to suggest that both these abnormalities of major histocompatibility complex expression preceded insulitis within a given islet. They also appeared to be unique to Type 1 diabetes, being absent in pancreases of patients with Type 2 (non-insulin-dependent) diabetes, chronic pancreatitis, cystic fibrosis, graft-versus-host disease and Coxsackie B viral pancreatitis. The development of autoimmunity to B cells in Type 1 diabetes may be a “multistep” process in which abnormalities of major histocompatibility complex expression on islet endocrine cells are crucial events.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00299027

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4

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Enteric cyst of the pancreas (1987)

Martin, Derrick F. ; Haboubi, Najib Y. ; Tweedle, David E. F.

Springer

Abdominal imaging 12 (1987), S. 35-36

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ISSN: 1432-0509

Keywords: Pancreas ; duplication cyst

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Enteric duplication cysts (enterogenous cysts) are found most commonly in the distal ileum, the posterior mediastinum, and the third part of the duodenum. Rarely, enteric cysts can occur distant from the gut. This paper describes the clinical and radiologic features of a cystic lesion in the body of the pancreas which was shown on resection to be an enteric cyst.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01885098

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5

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The increased echogenicity of the pancreas in infants and children: the white pancreas (1987)

Schneider, K. ; Harms, K. ; Fendel, H.

Springer

European journal of pediatrics 146 (1987), S. 508-511

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ISSN: 1432-1076

Keywords: Pancreas ; Ultrasound ; Haemosiderosis ; Cystic Fibrosis ; Pancreatitis

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract An increased echogenicity of the pancreas (“white pancreas”) was sonographically found in 25 children with various pancreatic and systemic diseases. Fifteen patients with cystic fibrosis had a small white pancreas. Five patients with haemosiderosis, two with pancreatitis and one with Shwachman-syndrome presented with a normal-sized or slightly enlarged pancreas. Fatty infiltration and calcifications of the pancreas can also increase its echogenicity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00441605

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6

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Correlation of abdominal CT imaging with autopsy findings in patients with malignant tumors (1987)

Winkelmann, M. ; Schoppe, W. D. ; Volk, N. ; [et al.]

Springer

Journal of cancer research and clinical oncology 113 (1987), S. 279-284

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ISSN: 1432-1335

Keywords: Computed tomography ; Liver ; Pancreas ; Adrenals ; Lymph nodes ; Autopsy

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary The value of abdominal computed tomography (CT) in diagnosing localized involvement of liver, pancreas, adrenals, and lymph nodes was evaluated in 117 patients with suspected or known malignant tumors by correlation with autopsy findings. Sensitivity, specificity, and accuracy of CT for localized liver disease was calculated to be 80% (84%), 96% (97%), and 90% (92%); for pancreatic tumors: 81% (86%), 98% (100%), and 95% (97%); for adrenal tumors: 65% (92%), 100% (100%), and 92% (98%); and for lymph node enlargement 75 (88%), 97% (98%), and 87% (94%), respectively. Results of routine evaluation could be improved, especially in the adrenal region, when scans were reevaluated by highly experienced examiners (results given in parenthesis). Computed tomography is a highly valuable diagnostic tool in the primary diagnosis and in the follow-up of tumor patients. The high costs are offset by a reduction in invasive procedures and a shortened hospital stay.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00396386

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7

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Neuron specific enolase demonstration in the diagnosis of a solid-cystic (papillary cystic) tumour of the pancreas (1987)

Chott, Andreas ; Klöppel, Günter ; Buxbaum, Peter ; [et al.]

Springer

Virchows Archiv 410 (1987), S. 397-402

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ISSN: 1432-2307

Keywords: Pancreas ; Solid-cystic tumour ; Neuron specific enolase

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Immunoreactivity to neuron specific enolase (NSE) was demonstrated in a solid-cystic (papillary cystic) tumour of the human pancreas, employing immunohistochemical methods. Positive staining for NSE was found with two different antisera. In addition, sodium-dodecyl-sulphate-polyacrylamide-gel-electro-phoresis (SDS-PAGE) of tumour homgenate revealed a distinct band reacting with a NSE antiserum. However, we failed to detect any hormonal products or neuroendocrine granules in the tumour. Therefore the authors advise caution in using the enzyme as a differential diagnostic tool, especially in surgical pathology of epithelial pancreatic neoplasms occurring in young females. In individual cases electron microscopy will be necessary since solid-cystic tumours of the pancreas consistently show large intracytoplasmic zymogen-like granules.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00712759

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8

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Neuropeptide Y: Intrapancreatic neuronal localization and effects on insulin secretion in the mouse (1987)

Pettersson, Magnus ; Ahrén, Bo ; Lundquist, Ingmar ; [et al.]

Springer

Cell & tissue research 248 (1987), S. 43-48

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ISSN: 1432-0878

Keywords: Neuropeptide Y ; Immunohistochemistry ; Pancreas ; Insulin secretion ; Mouse

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The intrapancreatic localization and the effects on basal and stimulated insulin secretion of neuropeptide Y (NPY) were investigated in the mouse. Immunocyto-chemistry showed NPY to be confined to intrapancreatic nerve fibers mainly associated with blood vessels. Fine varicose NPY fibers were also detected in the exocrine parenchyma and occasionally also within the islets. Double-staining experiments with the use of antisera for both NPY and tyrosine hydroxylase (TH) indicated that most of the NPY fibers were nonadrenergic in nature. Only a population of the NPY fibers occurring around blood vessels showed TH immunoreactivity. Under in vivo conditions, NPY was found to elevate plasma insulin levels slightly when injected intravenously at the high dose level of 8.5 nmol/kg. At lower dose levels, NPY did not affect basal plasma insulin levels, but instead inhibited glucose-induced insulin secretion. Thus, the glucose-induced increment in plasma insulin levels, which was 120±7μU/ml in controls, was reduced to 87 ±5 μU/ml by NPY at 4.25 nmol/kg (p〈0.01) and to 98±6μU/ml by NPY at 1.06 nmol/kg (p〈0.05). In contrast, the insulin secretory response to the cholinergic agonist carbachol was not affected by NPY. We conclude that NPY nerve fibers occur in the mouse pancreas and that most of these NPY nerve fibers are nonadrenergic. Furthermore, in the mouse, NPY enhances basal plasma insulin levels at high dose levels and inhibits glucose-induced, but not cholinergically induced insulin secretion at lower dose levels under in vivo conditions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01239960

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9

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Localization of thyrotropin-releasing hormone-and insulin-immunoreactivity in the pancreas of neonatal rats after injection of streptozotocin at birth (1987)

Leduque, P. ; Aratan-Spire, S. ; Wolf, B. ; [et al.]

Springer

Cell & tissue research 248 (1987), S. 89-94

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ISSN: 1432-0878

Keywords: TRH ; Insulin ; Pancreas ; Streptozotocin ; Regeneration ; Rat

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary Streptozotocin treatment at birth induces, in the pancreas of rats, first depletion of insulin and thyrotropin-releasing hormone and then early regeneration ofβ cells and insulin, but not TRH. This study was undertaken to investigate whether the reduction in pancreatic TRH content can be associated with changes in the intensity and the distribution of TRH-immunoreactivity, and to follow the pattern of regeneration ofβ cells through insulin- and TRH-immunoreactivity. In control animals, strong TRH-immunoreactivity was seen in insulin-containing cells on days 1–4 after birth. At day 7, the TRH-immunoreactivity was already decreased. In contrast, insulin-immunoreactivity was present throughout the neonatal period. A sparse population of cells near ducts also contained both TRH- and insulin-immunoreactivity at 1–2 days age. In streptozotocin-treated animals, TRH-immunoreactivity is found only in a few scattered insulin-containing cells in altered islets on days 1–4. Near the ducts, there were new insulin-containing cells which did not contain TRH. From day 7 regeneration of endocrine cells was characterized by new, typical islets, but these contained insulin-, but not TRH-immunoreactivity. These findings suggest a differential control of the biosynthesis of insulin and TRH within the pancreas.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01239967

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10

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Expression of cell type-specific markers during pancreatic development in the mouse: implications for pancreatic cell lineages (1987)

Teitelman, G. ; Lee, J. K. ; Alpert, S.

Springer

Cell & tissue research 250 (1987), S. 435-439

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ISSN: 1432-0878

Keywords: Pancreas ; Exocrine glands ; Islets of Langerhans ; Differentiation ; Immunocytochemistry ; Mouse

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The islet cells of the mammalian pancreas are comprised of four different endocrine cell types, each containing a specific hormone. Islet cells also contain two enzymes of the catecholamine biosynthetic pathway: tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). The cell lineage relationships of these different cell types have not been examined and it is not known whether, during development, they originate from the same or from different precursor populations. In this study we used immunocytochemical procedures to determine whether developing pancreatic cells express markers common to endocrine and exocrine cell types. We found that acinar cell precursors express AADC prior to the appearance of an exocrine marker and that the expression of AADC in acinar cells persists throughout embryogenesis to the first month of postnatal life. At this time, acinar cells do not contain AADC. We also found that exocrine cells containing AADC never express other islet-cell markers. These findings suggest that while acinar and islet cells both arise from precursor cells containing AADC, these progenitor cells do not express a combined endocrine-exocrine phenotype.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00219089

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11

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Complexes of 2,2′,2″-Nitrilotriphenol. Part 1. A Study of Bimolecular Nucleophilic Substitution at the Boron Atom (1987)

Müller, Edgar ; Bürgi, Hans-Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 499-510

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The tetradentate ligand 2,2′,2″-nitrilotriphenol forms a boron complex III with an intramolecular, transannular N→B dative bond of 1.68 Å in a strained tricyclo[3.3.3.0]undecane chelating system. The complex reacts with nitrogen bases L, such as pyridine, quinuclidine and others, to form complexes III-L, in which the intramolecular B-N bond is replaced by one between B and the external nucleophile. In solution, this displacement reaction is reversible. It was studied by temperature-dependent NMR spectroscopy. The resulting reaction and activation parameters suggest that the reaction is a bimolecular nucleophilic substitution (SN2).

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700303

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Complexes of 2,2′,2″-Nitrilotriphenol. Part 3. Crystal and Molecular Structures of Three Aluminium Complexes (1987)

Müller, Edgar ; Bürgi, Hans-Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 520-533

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Crystal and molecular structures of three Al(III) complexes of the tripod ligand 2,2′,2″-nitrilotriphenolate (I) are presented. They all show 5-coordinate Al in approximately trigonal bipyramidal geometry, with an external nucleophile X occupying the second axial position. X is OH- in[Al(I)(OH)]-[Hquin]+ (quin = quinuclidine), N in [Al(I)(py)] (py = pyridine), and one of the O-atoms of a second molecule in the dimeric [(Al(I))2]. Correlated variations in the axial bond lengths of the trigonal bipyramid are observed: [(Al(I))2]: Al-Nint. = 2.094 Å, Al-Oext. = 1.850 Å; [Al(I)(py)]: Al-Nint. = 2.153 Å, Al-Next., = 1.992 Å; [Al(I)(OH)]-: Al-Nint. = 2.278 Å, Al-Oext. = 1.765 Å. They are interpreted in terms of a dissociative reaction path at the Al(III) centre.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700305

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13

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Molluscicidal Saponins from Swartzia madagascariensis DESVAUX (1987)

Borel, Christian ; Hostettmann, Kurt

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 570-576

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The phytochemical investigation of the dried fruits of Swartzia madagascariensis (Leguminosae) afforded the five triterpenoid saponins 1-5. They were shown to be glucuronides of oleanolic acid and of gypsogenin by chemical and spectral means (FAB-MS, 13C-NMR, GC/MS). One of the isolated compounds, identified as 3-O-[O-α-L-rhamnopyranosyl-(1→3)-(β-D-glucopyranosyluronic acid)]oleanolic acid, was responsible for the high molluscicidal activity of Swartzia madagascariensis fruits against the schistosomiasis-transmitting snails Biomphalaria glabrata and Bulinus globosus.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700309

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14

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The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage (1987)

Burger, Ulrich ; Erne-Zellweger, Dominique ; Mayerl, Christa

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 587-592

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8. In contrast, porcine liver esterase (PLE, EC 3.1.1.1) cleanly hydrolyses 5 to give the isolable 1-methyl-2,4-cyclopentadiene-1-carboxylic acid (13). The latter undergoes thermal dimerization with conservation of the geminal-substitution pattern. The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C2 symmetry. Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acid concentration is used. The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700311

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15

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Potassium Carboxylates by Direct Carbonylation of Potassium Alkoxides (1987)

Rautenstrauch, Valentin

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 593-599

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Reaction of the K+ alkoxide of linalool (1) in benzene with CO at 425-440 bar and 120-130° for 12-30 h gave the K+ salt of 2,6-dimethyl-2-vinyl-5-heptenoic acid (4a) in a ca. 25% yield based on ca. 65% converted alkoxide. Reaction of the [K+ ⊂ 18-crown-6] alkoxide of 1 with CO at 50-55 bar and 40° for 90-140 h gave a mixture containing mainly the [K+ ⊂ 18-c-6] salts of 4a (ca. 62%) and of the homogeranic acids 3a and 6a (together ca. 27% of the mixture) in a ca. 35% combined yield based on 50-60% converted alkoxide. The uncomplexed or complexed K+ alkoxide of (S)-1 gave, with ca. 85% net retention, the K+ salt of (S)-4a. Reaction of the [K+ ⊂ 18-c-6] alkoxide of geraniol (2) with CO at 50 bar and 40° for 65-70 h gave myrcene (10) and geranyl formate (11) in a ca. 40-50% yield each based on ca. 85% converted alkoxide. Reaction of the [K+ ⊂ 18-c-6] alkoxide of 3-pentyl-1,4-pentadien-3-ol (14) at 50 bar and r.t. for 70 h gave a mixture of the [K+ ⊂ 18-c-6] salts of 2-pentyl-2-vinyl-3-butenoic acid (15a) (67%) and the 4-pentyl-2,4-hexadienoic acids 18a and 19a (together 23% of the mixture) in a ca. 90% combined yield based on ca. 65% converted alkoxide.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700312

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Synthesis and Copper(I) Complexes of a Series of 9- to 13-Membered N3 Macrocycles (1987)

Briellmann, Markus ; Kaderli, Susan ; Meyer, Charles J. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 680-689

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Eight cyclic triamines with ring sizes between 9 and 13 were synthesized by the p-toluenesulfonate method. The open-chain triamines bis(2-aminoethyl)amine (dien) and bis(3-aminopropyl)amine (diprop) were used as starting materials. In some cases, the corresponding dimeric cyclic hexaamines have been isolated and characterized as major by-products. The complexation of Cu(I) by the triamines has been studied potentiometrically in CH3CN/H2O. All ligands L form ternary complexes [Cu(CH3CN)L]+. The corresponding association constants vary between 1011 and 107, decreasing with increasing ring size. In addition, complexes [Cu(CH3CN)yLH]2+, y = 1 or 2, are found as less important species with maximum concentrations of 7 to 50%.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700318

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The Microstructure of Selective Palladium Hydrogenation Catalysts Supported on Calcium Carbonate and Modified by Lead (Lindlar Catalysts), Studied by Photoelectron Spectroscopy, Thermogravimetry, X-Ray Diffraction, and Electron MicroscopyThe following abbreviations and acronyms are used in the text: B. e. : Binding energy [eV], BET: Brunauer-Emmett-Teller (method of surface-area determination by physisorption of N2), AES: Auger electron spectroscopy, XPES: X-ray photoelectron spectroscopy, UPES: Ultraviolet photoelectron spectroscopy, ISS: Ionscattering spectroscopy, UHV: Ultrahigh vacuum (10-5 Pa), FTIR: Fourier-transform IR spectroscopy, TGA: Thermal gravimetric analysis, XRD: X-ray diffraction, XDA: Energy dispersive microanalysis, SEM: Scanning electron microscopy, TEM: Transmission electron microscopy, FWHM: Full width at half maximum. (1987)

Schlägl, Robert ; Noack, Klaus ; Zbinden, Heinz ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 627-679

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A detailed analysis of the system Pd + Pb on CaCO3 is presented. This system known as Lindlar catalyst is used for selective hydrogenations of C≡C bonds to C=C bonds. It was found to consist of seven distinct chemical phases. Essential ingredients are solid solutions of hydrogen and oxygen in Pd. The latter phase enables the metal particles to be attached to the support via an orientational relationship calcite (113)∥Pd + O (111). The addition of Pb neither changes the micromorphology of the disk-shaped Pd particles nor does it modify the electronic structure of Pd as studied by chemisorption experiments. The addition of Pb seems to block certain active sites and, thus, to enhance the selectivity. The support was found to be a multi-domain mixture of calcite and aragonite with domain sites of several hundred Å. The free surface of the pore-free solid is covered by a calcium-hydroxide carbonate. This phase as well as several other Pb phases seem to represent only spectator materials. Verification of this as well as finding the correlation between structure and function of the various components requires a kinetic analysis which is outside the scope of this paper. It is demonstrated that a variety of analytical techniques is required to unravel the complex nature of such a ‘simple' catalyst’ as it is Pd on CaCO3.

Additional Material: 36 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700317

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Verapliquinones: Novel Diprenylquinones from an Aplidium sp. (Ascidiacea) of Ile-Verte Waters, Brittany (1987)

Guella, Graziano ; Mancini, Ines ; Pietra, Francesco

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 621-626

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: An Aplidium sp. (Ascidiacea), collected in French Atlantic waters near the Ile Verte, is shown to contain verapliquinone B (2) and verapliquinone D (6) as the first examples of linear diprenylquinones of the neryl type, besides their respective isomers 1 and 5 of the geranyl type.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700316

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19

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Fe(II)-Induced Fragmentation Reaction of γ-Hydroperoxy-α,β-enones. Part 1. Synthesis of 13(14→8)-abeo-Steroids (1987)

Canonica†, Luigi ; Danieli, Bruno ; Lesma, Giordano ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 701-716

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Notes: Some steroidal analogues embodying the hitherto unknown 13(14→8)-abeo skeleton have been synthesized by Fe(II)-induced rearrangement (tandem β-fission/reductive alkylation) of 14α-hydroperoxy-7-en-6-ones. The configurational assignment was made by thorough analysis of NMR spectra; the structure of one of the products was unambiguously assessed by X-ray single-crystal analysis.

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Light-Induced, Thermal, and Acid-Catalyzed π-Skeletal Rearrangements of Five-Ring-Annelated HeptalenesPresented in part by H.-J.H. in a lecture at the ETH in Zürich, 1985. (1987)

Weber, Roland H. ; Brügger, Paul ; Jenny, Titus A. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 742-759

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Notes: It is shown that, upon irradiation in CDCl3 solution, 5,6,8,10-tetramethylheptalene-1,2-dicarboxylic anhydride (6) rearranges to its double-bond-shift (DBS) isomer 7 in an equilibrium reaction (Scheme 2). The isomer 7 is DBS stable at -50°. At ca. 30°, a thermal equilibrium with 97.8% of 6 and 2.2% of 7 is rapidly established. Similarly, the ‘ortho’-anhydrides 9 and 11 (Schemes 4 and 5) can be rearranged to their corresponding DBS isomers 12 and 13, respectively. Whereas 12 is DBS stable at 30° (at 100° in tetralin, 94.0% of 9 are in equilibrium with 6.0% of 12), the i-Pr-substituted isomer 13 is already at 30° in thermal equilibrium with 11 leading to 98.7% of 11 and 1.3% of 13. It is shown by rearrangement of diasteroisomeric ‘ortho’-anhydrides of known relative and absolute configuration (Scheme 6) that the DBS in such five-ring-annelated heptalenes occurs with retention of the configuration of the heptalene skeleton as already established for other heptalene compounds. It is found that the DBS process may also take place under acid catalysis (e.g. HCl/CH3OH), thus yielding 9 from 12 (Scheme 9). The ‘ortho’-anhydrides 21 and 23 (Scheme 10) which are isomeric with 9 and 11 (Scheme 3) undergo rapid DBS' already at room temperature. The thermal equilibrium 21⇄22 consists of 18% of 21 and 82% of 22 at 30° and that of 23⇄24 of 17% of 23 and 83% of 24 at -30°. From these equilibrium mixtures, the pure DBS isomer 22 can be obtained by crystallization. Again, these rapid DBS' occur with retention of configuration of the heptalene skeleton (Fig. 4).

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URL: http://dx.doi.org/10.1002/hlca.19870700323

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Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-PhenylnonafulvenHerrn Prof. Dr. Hans Nitschmann zum 80. Geburtstag gewidmet52. Mitt. über Fulvene, Fulvalene; 51. Mitt. [1]; Kurzmitt. [2]. (1987)

Furrer, Jürg ; Bönzli, Peter ; Frey, Alfred ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 862-880

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Notes: Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT-; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.

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Field-Desorption Mass Spectra of Fern Phloroglucinols Containing Three to Six Ring ConstituentsDedicated to the late Prof. Peter Brown (12.IX.1938-15.III.1981), Dept. of Chemistry, Arizona State University, Tempe, Arizona 08521, U.S.A., Whose premature death was a great loss to his friends and collegues. The last letter which we received from him (November 15, 1980) contained the first FD mass spectra of five relatively large fern phloroglucinols which he had successfully analyzed. Two of these spectra, in which no thermal rearrangement and /or fragmentation was observed, are reproduced in this article (1987)

Richter, Wilhelm J. ; Raschdorf, F. ; v. Euw, Josef ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 881-893

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Notes: It has been previously shown that the structural analysis of the title compounds by electron-impact ionization (EI)mass spectrometry is complicated by extensive, if not complete, thermal rottlerone-type rearrangement and/or fragmentation reactions. The use of a ‘softer’ ionization technique such as field desorption (FD) is, therefore, required in order that these compounds may be characterized in terms of their molecular size and composition. In this report, the FD mass spectra of typical representatives of this class of compounds are described along with the attempted suppression of undesirable thermal reactions by the optimization of the emitter temperatures.

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Structures and Electrical Properties of Some New Organic Conductors Derived from the Donor Molecule TMET (S,S,S,S,-Bis(dimethylethylenedithio) tetrathiafulvalene) (1987)

Karrer, Andreas ; Wallis, John D. ; Dunitz, Jack D. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 942-953

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Notes: Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf-6, AsF-6, SbF-6, I-3 (incommensurate), and 3:2 with tetrahedral anions BF-4, CIO-4, ReO-4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.

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Bildung tricyclischer Thietan-Derivate durch intramolekulare(2+2)-Cycloaddition (1987)

Wipf, Peter ; Heimgartner, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 992-994

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Notes: Formation of Thietane Derivatives via Intramolecular (2+2) CycloadditionOn irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b, synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a,b, undergo an intramolecular (2+2)-cycloaddition reaction of the C=S and C=C bonds to give the tricyclic thietane derivatives 3a,b.

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Photochemical Synthesis of 2-Alkylidene-1,3-cyclocalkanediones. Preliminary Communication (1987)

Hobel, Klaus ; Margaretha, Paul

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 995-996

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Notes: Photolysis (λ = 254 nm) of 4-(tert-butyl)-4,6,7,8-tetrahydro-7,7-dimethy-2H-1-benzopyran-2,5(3H)-dione (3a) in t-BuOH affords 2-(2,2-dimethylpropylidene)-5,5-dimethyl-1,3-cyclohexanedione (1a) in 80% yield via homolysis of the lactone O—CO bond and subsequent ketene elimination.

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Some Cyclic Oligopeptide with S2n Symmetry (1987)

Tomasic, Lera ; Lorenzi, Gian Paolo

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1012-1016

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Notes: Some cyclic oligopeptides formed by an equal number of alternating D- and L-amino-acid residues have been synthesized by using the hydrochloride of the open-chain peptide acid as precursor and the mixed-anhydride condensation method. The cyclic oligopeptides (tetra-, hexa-, and octavaline, hexaleucine, and hexaphenylalanine) form very stable H-bonded structures (IR-amide band at 3270-3290 cm-1) which are insoluble in common organic solvents. In CF3COOH/CDCI3 (25°), they yield 1H-NMR spectra snowing the expected equivalency of the various amino-acid residues.

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Strukturaufklärung ungewöhnlicher Umlagerungsprodukte von S-(1-Alkenyl)sulfoximiden mit Hilfe der Stossaktivierungsmassenspektrometrie (CAD-MS) (1987)

Veith, Hans-Jürgen ; Gais, Hans-Joachim ; Erdelmeier, Irene

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1041-1049

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Notes: Structure Determination of Unusual Rearrangement Products of S-(1-Alkenyl)sulfoximides by Collisionally Activated Dissoication Mass Spectrometry (CAD-MS)The Molecular ions of s-(l-alkenyl)--N-(p-tolyl)sulfoximides 1 are transformed into the N(phenylsufenyl)sulfonamides 3+ by a 1,2-migration of the alkenyle group to the O-atom of the sulfoximide function followed by a 2,3-sigmatropic rearrangement. The structure of the production e has been unambiguouslydetermined by the CAD method, showing the identity of the ion e (m/z368) obtained from 1a and from 4a.

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Reaktionen von 1,2-Bis(trimethylsilyl)iminen mit Selen-und Tellur-halogeniden (1987)

Neidlein, Richard ; Knecht, Dagmar

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1076-1078

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Notes: Reactions of 1,2-Bis(trimethylsilyl)imines with Selenium and Tellurium HalogenidesThe reactions of benzil-bis(trimethylsily)imine and phenanthrene-9,10-bis(trimethylsilyl)imine with SeOCl2, SeCl4 and TeCl4 are described.

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Remote Tricarbonyl(diene)iron Substituent Effect on Ester Heterolysis. The Solvolyses of 5,6,7,8-Tetramethylidenebicyclo[2.2.2]oct-2-yl Methanesulfonate and of its Tricarbonyliron Mono- and Dinuclear ComplexesPart of Ph.D. thesis of J.-C. Zwick, Ecole Polytechnique Fédérale de Lausanne, 1987. Part of this work has been presented at the Fall Meeting of the Swiss Chemical Society in Bern, Oct. 10, 1986. (1987)

Zwick, Jean-Christophe ; Gabioud, Rapny ; Vogel, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1079-1094

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Notes: Buffered acetolyses and hydrolyses of 5,6,7,8-tetramethylidenbicyclo[2.2.2]oct-2-yl methanesulfonate (17), of its ‘syn-endo’ (18), ‘syn-exo’ (19), ‘anti-endo’ (20), ‘anti-exo’ (21) tricarbonyliron complexes and of its ‘anti-exo,syn-endo’ (22) and ‘anti-endo,syn-exo’ (23) bis(tricarbonyliron) dinuclear complexes have been investigated (product analysis and kinetics). In contract with the solvolyses of the uncomplexed mesylate 17, the solvolyses of the complexed esters can be highly chemo- and stereoselective. The nature of the products (non-rearranged bicyclo[2.2.2]oct-2yl vs. rearranged bicyclo[3.2.1]oct-2-yl derivatives) depends on the relative configuration of the tricarbonyl(diene)iron moieties and on the medium. The rates of solvolyses of 17 are only slightly affected by complexation of one or both s-cis-butadiene units with Fe(CO)3 groups, except in the cases where the diene moiety ‘anti’ with respect to the mesylate is complexed onto its ‘endo’ face (20,23). In these cases, significant rate-retardation effects are observed, consistent with the inductive effect of the Fe(CO)3 substituent. Such retardation effects are overwhelmed by competing accelerating homoallylic participation by uncoordinated ‘anti’ -diene moieties (18,19) or, as in the case of the ‘anti-exo’-Fe(CO)3 complexes 21 and 22, by possible direct metal participation to the ionization process.

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Synthetic Models of the Active Site of Cytochrome P-450. 1st Communication. The Synthesis of a Doubly-Bridged Iron(II)-Porphyrin Carrying a Tightly Bound Thiolate LigandPresented in part at the ‘Gordon Research Conference’ on the ‘Chemistry and Biology of Pyrroles’, New Hampshire, 27.7.-1.8.86 (W.-D.W.), and at the ‘Swiss Chemical Society’ meeting, Bern, 10.10.86 (B.S.). (1987)

Stäubli, Beat ; Fretz, Heinz ; Piantini, Umberto ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1173-1193

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Notes: The doubly-bridged iron(II)-tetraphenylporphyrin derivative 6, carrying a sterically fixed S- ligand in the ‘proximal’ position and the substrate at the ‘distal’ site, was synthesised as an enzyme model for cytochrome P-450. Compound 36, the CO complex of 6, displays a split Soret band (403 and 457 nm) similar to the native cytochrome P-450.

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Stereoselektive Alkylierung an C(α) von Serin, Glycerinsäure, Threonin und Weinsäure über heterocyclische Enolate mit exocyclischer DoppelbindungZughörige Kurzmitteilungen: [1] (Weinsäre) [2] (Threonin) [3] (Serin) [4] (Glycerinsäure).Siehe auch die Diskussionen in den vor kurzem erschienenen Übersichtsartikeln [5][6]. (1987)

Seebach, Dieter ; Aebi, Johannes D. ; Gander-Coquoz, Marlyse ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1194-1216

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Notes: Steroselective Alkylation at C(α) of Serine, Clyceric Acid, Threonine, and Tartaric Acid Involving Heterocyclic Enolates with Evocyelic Double BondsThe chiral, non-racemic title acids are converted to methyl dioxolane-(cf. 13), oxazoline-(4) and oxazolidinecarboxylates (cf. 9). Deprotonation by Li(i-Pr) 2N at dry-ice temperature gives solutions of the lithium enolates A-D With exocyclic enolate double bonds. These are stable crough with respect to β-elimination (Scheme 1) to be alkylated with or without cosolvents such as HMPA or DMPU The products are formed in good to excellent yields and, with the exception of the tartrate-derived acetonlde (see Scheme 2), with diastereoselectivities above 90%. While the tartrate-and threonine-derived enolates (A and B, resp.) are chiral due to the second stereogenic center of the precursors, the serine- and glyceric-acid-derived enolates (Aand B, resp.) are chiral due to the second sterogenic center of the precursors, the serine-nd glyceric-acid-derived enolates are non-racemic due to a tert butyl-substituted (pivalaldehyde-derived) acetal center (C and D, resp.). The products of alkylation can be hydrolyzed to give α-branched tartaric acid (Scheme 2), allothreonine (Scheme 3), serine (Scheme 4), and glyceric-acid derivatives (Scheme 5) with quaternary stereogenic centers. The configurations of the products are determined by NOE-NMR measurements and by chemical correlation. These show that the dioxolane-derived enolates A and D are alkylated preferentially from that face of the ring which is already substituted (‘syn’-attack), while the dihydrooxazol-and oxazolidine-derived enolates B and C are alkylated from the opposite face (‘anti’-attack). The ‘syn’-attack is postulated to arise from strong folding of the heterocyclic ring due to electronic repulsion between the enolate π-system and non-bonding electron pairs on the heteroatoms (see Scheme 6).

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Novel Synthesis of Agaritine, a 4-Hydrazinobenzyl-Alcohol Derivative Occurring in Agaricaceae (1987)

Datta, Subir ; Hoesch, Lienhard

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1261-1267

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Notes: The 4-hydrazinobenzyl alcohol (3 was prepared (58%)) by diiobutylaluminiumhydride reduction of methyl 4-hydrazinobenzoate (4), whereas LiA1H4 or LiBh4 reduction of4 proceeded further to yield (via intermediate 3) (4-tolyl)hydrazine (5). The alcohol 3 was stable under O2-free conditions and exhibited no tendency to eliminate H2O, neither thermally nor with H+ catalysis. Oxidation of 3 with SeO2 yielded 4-(hydroxymethyl)benzine-diazonium ion (8), identified by its azo coupling product 9 with 2-naphthol. Condensation of 3 with 1-benzyl 5-Hydrogen N-(benzyloxycarbonyl)-L-glutamate (10) in presence of dicyclohexylcarbodiimide afforded 81% of N2-(benzyloxycarbonyl)-L- glutamic acid 1-(benzyl-ester) 5-{2-[4-(hydroxymethyl)phenyl]hydrazide} (11) which upon controlled hydrogenolysis (quinoline-sulfur-poisoned Pd/C catalyst) gave 82% of L-Glutamic acid 5-{2-[4-(hydroxymethyl)phenyl] hydrazide} (1), i. e. agaritine, a metabolite of Agaricus bisporus. Without poisoning of the catalyst, hydrogenolysis of (11) yielded L-glutamic acid 5-[2-(4-tolyl)hydrazide] (12).

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The Solid and Solution Conformations of (±)-Corycavine (1987)

Kamigauchi, Miyoko ; Iwasa, Kinuko ; Takao, Narao ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1482-1486

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Notes: The crystal structure of corycavine, a protopine-type alkaloid, has been determined by X-ray analysis. A conformational feature observed is the existence of a strong electrostade interaction between the N- and C-atom at a distance of 2.618 Å. Such an interaction stabilizes the 10-membered ring conformation of the structure. Analyses of NMR spectra indicate that corycavine has the same conformation in solution as in the crystal state.

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Dimethylformamide-Exchange Mechanism on Some First-Row Divalent Transition-Metal IonsPart 33 of the series ‘High-Pressur NMR Study’. Part 32: [1].Taken in part from the diploma work of C. Cossy, Université de Lausanne, 1983.This work was presented in part at the 24th International Conference on Coordination Chemistry, Athens, Greece, August 1986. (1987)

Cossy, Cédric ; Helm, Lothar ; Merbach, André E.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1516-1525

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Notes: The effect of temperature on the dimethylformamide exchange on Mn(DMF)2+6 and Fe(DMF)2+6 has been studied by 13C- and 17O-NMR, respectively, yielding the following kinetic parameters: k298 equals; (2.2±0.2). 106 S-1, ΔH≠ = 34.6 ± 1.3 kJ mol-1, ΔS≠ = -7.4 ± 4.8 J K-1mol-1 for Mn2+ and K298 = (9.7 ± 0.2).105 S-1, Delta;H≠ = 43.0 ± 0.9 kJ mol-1, ΔS≠ = + 13.8 ± 2.8 J K-1mol-1 for Fe2+. The volumes of activation, ΔV≠ in cm3mol-1, derived from high-pressure NMR on these metal ions, together with the previously published activation volumes for Co2+ and Ni2+ (+2.4 ± 0.2 (Mn2+), +8.5 ± 0.4 (Fe2+) +9.2 ± 0.3 (Co2+), + 9.1 ± 0.3 (Ni2+)) give evidence for a dissociative activation mode for DMF exchange on these high-spin first-row transition-metal divalent ions. The small positive ΔV≠ value observed for DMF exchange on Mn2+ seems to indicate that a mechanistic changeover also occurs along the series, (probably from Id to D), as for the other solvents previously studied (Ia to Id, for H2O, MeOH, MeCN). This changeover is shifted to the earlier elements of the series, due to more pronounced steric crowding for dimethylformamide hexasolvates.

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Two New Antifungal Naphthoxirene Derivatives and their Glucosides from Sesamum angolense WELW (1987)

Potterat, Olivier ; Stoeckli-Evans, Helen ; Msonthi, Jerome D. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1551-1557

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Notes: Two novel naphthoxirene derivatives 1 and 2 their glucosides 3 and 4 have been isolated from the root bark of Sesamum angolense Welw. (Pedaliaceae) by preparative liquid chromatography. The structure of 1 was established by X-ray diffraction analysis. The identities of the other naphthcxirenes were deduced by spectroscopic (IR, UV, 1H-NMR, 13C-NMR, EI-MS, DCI-MS) and chemical methods (oxidation, acid and enzymatic hydrolysis). Compounds 1-3 exhibited antifungal activity. Naphthoxirene 1 was, in addition, cytotoxic to human colon carcinoma cells.

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On Negative Birefringence in Water-in-Oil Microemulsions (1987)

Hilfiker, Rolf ; Eicke, Hans-Friedrich ; Hammerich, Holger

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1531-1536

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Notes: The occurrence of a negative birefringence in water-in-oil (W/O) microemulsions has been substantiated and analyzed. The analysis is based on the well-established aqueous nanodroplet model of W/O microemulsions. In the particularly investigated water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/aliphatic oil systems, the AOT monolayer exhibits a negative induced intrinsic birefringence, which is brought about by the pronounced polarizability of the alkyl moiety of the AOT molecule approximately perpendicular to the direction of its permanent dipolement.

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URL: http://dx.doi.org/10.1002/hlca.19870700610

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Erratum (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 2246-2246

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19870700829

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Mitteilungen - Communications (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 2305-2306

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URL: http://dx.doi.org/10.1002/hlca.19870700830

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Herstellung und Charakterisierung in Membranen von Ionophoren mit Selektivität fü Natrium-Ionen (1987)

Bongardt, Frank ; Vögtle, Fritz ; Wegmann, Dorothée ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 153-157

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Notes: Preparation of Neutral Sodium-Selective Ionophores and their Characterization in Membrane ElectrodesDifferent ionopbores based on N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide (1) have been prepared by substitution of the aromatic ring carrying the ether O-atoms. Substituents of widely different electronegativity (CH3, CH3O, CHO, CN NO2, Br) do not relevantly influence the ion selectivity.

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URL: http://dx.doi.org/10.1002/hlca.19870700119

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Complexes of 3,3′-Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans-Spanning Bidenatate Chelates?? (1987)

Marty, Werner ; Kapoor, Pramesh N. ; Bürgi, Hans-Beat ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 158-170

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Notes: The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] (1) forms monomeric, trans-square-planar complexes MX2(1) (M = Ni, Pd, Pt; X = Cl-, Br- I-, and, in part, N3-, NCS-, CN-, NO3-) as well as Pt(H)Cl(1), Pt(H)Br(1), and RhCl(CO)(1). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl2(1)]2 and cis-[PtCl2(1)]n (mean value of n ≈ 4-5) 31P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl(1)·0.5 (CH3)2C=O·0.39 C6H12 (space group C2/c,a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 Å3, Z = 8) confirms the presence of three-coordinate Ag(I), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).

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URL: http://dx.doi.org/10.1002/hlca.19870700120

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Aza-2-dienes-1,3. Partie 5. Préparation de N-aminoimidazoles, 3H-pyrroles, triazolo[1,2,4][1,5-a]pyrazines et imidazo[1,2-a]pyrazines (1987)

Legroux, Didier ; Schoeni, Jean-Paul ; Pont, Christiane ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 187-195

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Notes: 2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazinesNucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.

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Syntheses of Tetrahydrolipstatin and Absolute Configuration of Tetrahydrolipstatin and Lipstatin (1987)

Barbier, Pierre ; Schneider, Fernand

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 196-202

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Notes: Lipstatin (1), a natural product, and tetrahydrolipstatin (2) are pancreatic lipase inhibitors. Non-stereoselective and partially stereoselective syntheses of 2 are used to establish the absolute configuration of tetrahydrolipstatin and lipstatin.

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Ring-Open Analogues of Adenine Nucleoside. Aminoacyl Derivatives of Cyclo- and Acyclo-Nucleosides (1987)

Hakimelahi, Gholam H. ; Zarrinehzad, Morteza ; Jarrahpour, Ali A. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 219-231

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Notes: The synthesis of acyclic analogues of ribo- and deoxyribonucleosides is described. These compounds (Table 3) are both poor substrates and poor inhibitors of adenosine deaminase. The synthesis of dinucleotides from these analogues is also described, and the activity along with the inhibitory properties of some of them are studied against deaminase enzyme. These nucleotides are resistant to degradation by phosphodiesterases. HCl impregnated on silica gel is an excellent reagent for the preparation of the chloromethyl ether precursors of acyclo-nucleosides. A general and rapid procedure is developed for the preparation and isolation of the 5′-aminoacyl derivatives of robo- and arabinonucleosides. Quinoline has a marked effect on aminoacylations without racemization. Compounds 35a, b possess remarkable antiviral effects in vitro. A procedure is also developed for the conversion of acyclo-ribonucliosides 13e, f to acyclo-deoxyribonucleosides 11e, f.

Additional Material: 4 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700127

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Functionalisation of saturated hydrocarbons. Part 9Part 8:[1].. Oxidation of patchouli alcohol by the ‘gif system’: Isolation and organoleptic properties of three new ketonic derivativesDedicated to Prof. Vlado Prelog on the occasion of his 80th birthday (1987)

Barton, Derek H. R. ; Belœil, Jean-Claude ; Billion, Annick ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 273-280

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Notes: Oxidation of patchouli alcohol (1) using the ‘Gif system’ afforded as major isolated products three new ketonic derivatives 16-18. The structures of these compounds were established by spectral techniques including 2D-NMR. Ketones 16-18 display interesting organoleptic properties.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700202

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Synthese von ω-(5-Oxo-1-cyclopentenyl)alkansäure-methylestern aus 2-Nitrocycloalkanonen (1987)

Stach, Hans ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 315-320

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Notes: Synthesis of Methyl ω-(5-Oxo-1-cyclopentenyl)alkanoates Starting from 2-NitrocycloalkanonesA convenient synthesis of methyl ω-(5-oxo-1-cyclopentenyl)alkanoates 1 is described. 2-Nitrocycloalkanones 2 are converted to 2-(3,3-dimethoxypropy1)-2-nitrocycloalkanones 4. Treatment of 4 with MeOH/MeONa led to the ring-opened nitronates 5 which underwent a Nef reaction to form the corresponding oxo derivatives 6. Partial hydrolysis of followed by base-catalyzed aldol reaction gave the desired products in high yields.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700207

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Cyclobut-2-enones from Alkynes via Dichlorocyclobut-2-enonesIn part taken from the Ph.D. thesis of A.A.A., University of Zürich, 1986. (1987)

Ammann, Adrian A. ; Rey, Max ; Dreiding, André S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 321-328

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Notes: The [2 + 2]-cycloaddition of dichloroketene (prepared in situ from CCl3COCl and Zn(Cu)) with three alkynes 1a-c to form 2,3-dimethyl-(2a), 2,3-diethyl-(2b) and 3-butyl-4,4-dichlorocyclobut-2-enone (2c) proceeds rapidly in the absence of POCl3. The primary products 2a-c rearrange in situ to the 2,4-dichlorocyclobut-2-enones 3a-c under the influence of ZnCL2 produced during the reaction. ZnCl2 converts both 2a and 3a into a 4:6 equilibrium mixture of the two; this isomerization does not occur with LiCl. The Cl-atoms of both 2a, b and 3a, band of 2c may reductively be removed with Zn(Cu) in AcOH/pyridine to afford the alkylcyclobutenones 4a-c. Without pyridine, this reduction gives ca. 1:1 mixtures of the double-bond isomers 4 and 5 in low yields. The cyclobutenones 2c and 4c may be deuterated by CD3COOD in the presence of pyridine. D-Atom is introduced into 2c at C(4) and at C(γ), and into 4c at C(2) and C(4). A mechanism for this deuteration is considered, which does not involve a cyclobutadienolate 7, but rather a cyclobutenolate of type 8. The reductions of 2 and 3 to 4 might also pass through the same type of intermediate 8.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700208

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3-(Dimethylamino)-2,2-dimethyl-2H-azirin als α-Aminoisobuttersäure(Aib)-Äquivalent: Cyclische Depsipeptide durch direkte Amid-CyclisierungVorläufige Mitteilung s. [1]; vgl. auch [2]. (1987)

Obrecht, Daniel ; Heimgartner, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 329-338

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Notes: 3-(Dimethylamino)-2,2-dimethyl-2H,-azirine as an α-Aminoisobutyric-Acid (Aib) Equivalent: Cyclic Depsipeptides via Direct Amid CyclizationIn MeCN at room temperature, 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1) and α-hydroxycarboxylic acids react to give diamides of type 8 (Scheme 3). Selective cleavage of the terminal N,N-dimethylcarboxamide group in MeCN/H2O leads to the corresponding carboxylic acids 13 (Scheme 4). In toluene/PhSH, phenyl thioesters of type 11 are formed (see also Scheme 5). Starting with diamides 8, the formation of morpholin-2,5- diones 10 has been achieved either by direct amide cyclization via intermediate 1,3-oxazol-5(4H)-ones 9 or via base-catalyzed cyclization of the phenyl thioesters 11 (Scheme 3). Reaction of carboxylic acids with 1, followed by selective amide hydrolysis, has been used for the construction of peptides from α-hydroxy carboxylic acids and repetitive α-aminoisobutyric-acid (Aib) units (Scheme 4). Cyclization of 14a, 17a, and 20a with HCI in toluene at 100° gave the 9-, 12-, and 15-membered cyclic depsipeptides 15, 18, and 21, respectively.

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Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid (1987)

Stach, Hans ; Huggenberg, Walter ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 369-374

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Keywords: Chemistry ; Organic Chemistry

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Notes: Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olidThe title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3a). The key step in this transformation is the isomerization of the C=C bond in 3a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid (11a), which, after hydrolysis and decarboxylation, gave 13a. In addition, the syntheses of five other compounds related to 13a are reported.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700214

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Triaziridine 7. Mitteilung6. Mitteilung: [1].. Stabile pyramidale Konfigurationen an den Stickstoff-Atomen von Dialkyl-und Trialkyl-triaziridinen (1987)

Hilpert, Hans ; Hoesch, Lienhard ; Dreiding, André S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 381-389

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Notes: Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl-and Trialkyl-triaziridinesStereochemical features of the recently synthesized nine samples of di- and trialkyl-triaziridines, namely the 1,3-cyclopentylen-(series a) and the two stereoisomers of the diisopropyl derivatives (series b and c), containing as the third substituent an H-atom (2), a CH3 group (3)or a CH2OH group (4), were elaborated on the basis of the 1H-, 13C-, and 15N-NMR spectra. The three N-atoms of the saturated N3-homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2-4 of the series a and b possess twofold symmetry (Cs), while 2-4 of series c are asymmetric. Thus, series c has the trans-configuration at N(2)/N(3) and, consequently, the cis-configuration at N(1)/N(2), while series a and b have the cis-configuration at N(2)/N(3) and -since the all-cis-arrangement is excluded-the trans-configuration at N(1)/N(2). The asymmetry of the trans-configurated 2c turned into twofold symmetry (C2), when a little CF3COOH was added. The 1H- and 13C-NMR data of series b and c of our alkyl-triaziridines exhibit a shielding effect, according to which there are two types of i-Pr groups, i-Pr(a) and i-Pr(b). They differ in the NMR signals of the H- and the C-atoms of their CH groups: the H-atoms of i-Pr(a) are more deshielded by 0.75-1.111 ppm and its C-atoms are more shielded by 10.0-160.0 ppm as compared to the corresponding atoms of i-Pr(b). i-Pr(a) is cis (on the N3-homocycle) to a large substituent (such as i-Pr, Me, CH2OH) and to a lone pair, while i-Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH3 and CH2OH groups at N(1) of 3 and 4 in the series b and c.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700216

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Synthese eines Nickel(II)-B,C,D-hexadehydrocorrinats durch (A→D)-CyclisierungKurzmitteilung: [1].Professor Dr. Gerhard Quinkert zum 60. Geburtstag gewidmet (1987)

Montforts, Franz-Peter ; Bats, Jan W.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 402-411

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Notes: Synthesis of a Nickel(II) B,C,D-Hexadehydrocorrinate by (A→D)-Ring ClosureThe B,C,D-hexadehydrocorrin of type 10 fills a gap in the corrin family whose members can occur at different oxidation levels. We report here on the synthesis of a correspondingly protected secocorrin 23 and its convenient cyclization to 10

Additional Material: 3 Tab.

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Studies on the Biosynthesis of Tabtoxin (Wildfire Toxin). Origin of the Carbonyl C-Atom of the β-Lactam Moiety from the C1-Pool (1987)

Müller, Barbara ; Hädener, Alfons ; Tamm, Christoph

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 412-422

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Notes: Re-isolation of Pseudomonas tabaci strain NCPPB 2730 from its host, the tobacco plant, led to an activation of the bacteria in order to produce the β-lactam dipeptide tabtoxin (Wildfire toxin, 1). Incorporation of several 14C-labelled amino acids as well as L-[methyl-13C]methionine, L-[1,2-13C2]- and L-[3,4-13C2]aspartate, rac -[1,2-13C2]glycerol, and [1,2-13C2]acetate into isotabtoxion (2) demonstrated that the building blocks of tabtoxin (1) are L-threonine, L-aspartate, the Me group of L-methionine and a C2-unit derived from the C3-pool (Fig. 3). The Me group of L-methionine provides the carbonyl C-atom of the β-lactam moiety. These findings represent a novel pathway in β-lactam biosynthesis. Mechanistic aspects with respect to the β-lactam ring formation are discussed. A biradical 16 is proposed as an intermediate during the cyclization of a N-formyl-α-amino ketone 15.

Additional Material: 2 Ill.

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Mitteilungen - Communications (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 488-491

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Keywords: Chemistry ; Organic Chemistry

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URL: http://dx.doi.org/10.1002/hlca.19870700229

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On the Purported Structure of Cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (1987)

Gleiter, Rolf ; Schaaff, Hans Peter ; Rodewald, Hans ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 480-487

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Notes: The reaction of the bis(sulfonium salt)7 in a solution of Na2CO3 in H2O/EtOH yielded three main products 8-10. The spectroscopic data of 8 were identical to those which led Mithcell and Sondheimer to assign them to cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (3). Our investigations show, however, that the correct structural assignment leads to the structure of 7,7a-dihydrodibenzo[de,mn]naphthacene (8).

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700228

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Masthead (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987)

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URL: http://dx.doi.org/10.1002/hlca.19870700101

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Mehrstufige Redoxsysteme. XLIX. MitteilungXLVIII. Mitteilung:[1]. Mit π-Systemen substituierte 1,3-Dimethylidencyclobutane: Synthese und Eigenschaften (1987)

Freund, Wolfgang ; Hünig, Siegfried

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 929-941

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Notes: Multistep Redox Systems. 1,3-Dimethylidenecyclobutanes Substituted by π-Syntheses and PropertiesAs potential redox systems 1,3-dimethylidenecyclobutanes are synthesized in which the ‘exo’-methylidene group participates in a cyclopentadienyl (typeC4)or cycloheptatrienyl (type A5) system. Benzo-annellated systems are also described. The formation of the C=C bond by the reaction of thioketones (3 and 31) with diazo compounds is extended to extended to 1,6,7,21, and 24, which so far had not been employed. In some cases, intermediate thiiranes can be isolated (e.g.4) which are smoothly transformed into the target compounds of types C4 and A5 by extrusion of sulfur. The new C=C bonds may be introduced stepwise, thereby allowing the synthesis of unsymmetrically substituted 1,3-dimethylidenecyclobutanes (e.g. 20 and 35). Reduction of by Na does not produce bicyclobutanes but compounds 43 and 44 with one dihydrofulvene unit.

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Verecynarmin A, a Novel Briarane Diterpenoid Isolated from Both the Mediterranean Nudibranch Molluse Armina maculata and its Prey, the Pennatulacean Octocoral Veretillum cynomorium (1987)

Guerriero, Antonio ; D'Ambrosio, Michele ; Pietra, Francesco

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 984-991

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The briarane diterpenoid verecynarmin A (=(-)).(8R,9S,11R,12aR,4Z,6Z)-11,12-epoxy-8,8a,9,10,12,12a,13-octahydro-1,5,8a,12-tetramethylbenzo[4,5]cyclodeca[1,2-b]furan-9-yl acetate; ((-)-1) is shown to be contained in both the Mediterranean nudibranch mollusc Armina maculata(RAFINESQUE) and its prey, the pennatulacean octocoral Veretillum cynomorium(PALLAS). The structure is mainly solved by 1D-NMR, 2D-NMR, and NOE studies of (-)-1. However, the relative configurations at the epoxide and angular methyl centres, as well as the preferred conformation, are established by shift-reagent and NOE studies of diol(-)-4 obtained by epoxide-ring opening of (-)-1 with LiA1H4. The absolute configuration is established via deacetylation of (-)01 followed by Horeau's esterification.

Additional Material: 1 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700408

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Oxidationsreaktionen methyl-substituierter 2,1,3-Benzothiadiazole und 2,1,3-Benzoselenadiazole mit Selen-dioxid (1987)

Neidlein, Richard ; Knecht, Dagmar

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 997-1000

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Oxidation Reactions of Methyl Substituted 2,1,3-Benzothiadiazoles and 2,1,3-Benzoselenadiazoles with Selenium DioxideThe synthesis 5-8 by oxidation of 4-methyl-(1),5-methyl(2), 5,6-dimethyl-2,1,3-benzoselenadiazole (3), and 5,6-dimethyl-2,1,3-benzothiadiazole (4), respectively, with selenium dioxide as well as their spectroscopic properties are described.

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URL: http://dx.doi.org/10.1002/hlca.19870700411

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Steric Effects on Reaction Rates. Part IX. Force-Field Parameters for Bridgehead and Rigid Tertiary Carbenium Ions (1987)

Müller, Paul ; Mareda, Jiri

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1017-1024

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Molecular-mechanics calculations for strain of carbenium ions are tested using Bentley's unified reactivity scale for bridgehead solvolysis as reference. Excellent correlations are obtained for solvolytic bridgehead reactivity with the calculated steric-energy difference (ΔEst) between substrate (R—H or R—OH) and cation (R+). After adjustment of appropriate force-field parameters, the approach is successfully extended to the rigid, but planar cations derived from structures 15-20; however, the general set of parameters cannot be applied to highly strained systems such as the cation formed from 17. With all of the 18 sets of parameters tested, the 2-endo-norbornyl derivative 16, is adequately correlated, while the exo isomer 15 exhibits enhanced reactivity by a factor of ca. 102 to 103.

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700414

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Complexes of 2,2′,2″-Nirtilotriphenol. Part IV. Cage Compounds with Phosphorus(III) and Phosphorus(V) (1987)

Müller, Edgar ; Bürgi, Hans Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1063-1069

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The ligand 2,2′,2″-nitrilotriphenol reacts with P(III) and P(V) compounds to form corresponding phosphorus complexes. Syntheses and NMR data of 2,2′,2″-nitrilotriphenyl phosphite (II), 2,2′,2″-nitrilotriphenyl phosphate (III) and of a hydrolysis product of II, 2,2′-[N-(2-hydroxyphenyl)imino]diphenly phosphonate (IV), are reported, as well as crystal structures of II and IV. Phosphite II shows a bicycloundecane framework; no NċPinteraction is present. The phosphonate IV shows two coordinated and one dangling phenol group; the N-atom does not interact with the P-atom. Strong acids protonate II as well as III to form cations: in these, NMR evidence indicates coordination of the N-atom to the P-atom.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700418

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Octacarbonyldicoblat-Inauced (1,3) H Shits in 1-Methylallenecarboxylates and Allenic LactonesDedicated to Professor Dr. André S. Dreiding (1987)

Trifonov, Latchezar S. ; Orahovats, Alaxander S. ; Heimgartner, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1070-1075

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The allenecarboxylates 1a,b and allenic lactones 4a,b undergo thermally induced (1,3) H Shifts in the presence of Co2(CO)8. The non-isolated 1,3-dienes 2a,b react further affording the Diels-Alder Adducts 3a,b Scheme 1 in high yields. These adducts were not formed in the case of the 2-vinybutenolides 5a,b. On irradiationin the presence of Co2(CO)8 or Mn2(Co)10, the studied allenes reacted in a different manner, yielding either cyclization products 7 and 8 (Scheme 3) or products 9 and 10, formed via H abstracton and solvent addition (Schemes 4 and 5).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700419

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Brominations of Cyclic Acetals from α-Amino Acids and α- or β-Hydroxy Acids with N-Bromosucinimide (1987)

Zimmermann, Jürg ; Seebach, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1104-1114

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The preparation of novel electrophilic building blocks for the synthesis of enantiomerically pure compounds (EPC) is described. Thus, the 2-(tert-butyl)dioxolanones, -oxazolidinones, -imidazolidinones, and -dioxanones obtained by acetalization of pivalaldehyde with 2-hydroxy-, 3-hydroxy-, or 2-amino-carboxylic acids are treated with N-bromosuccinimide under typical radical-chain reaction conditions (azoisobuytyronitril/CCl4/reflux). Products of bromination in the α-position of the carbonyl group of the five-membered-ring acetals are isolated or identified (2, 5, and 8; Scheme 1). The dioxanones are converted to 2H, 4H-dioxinones under these conditions (12, 14, 15, 21, and 22; Schemes 2 and 3). The products can be converted to chiral derivatives of pyruvic acid (methylidene derivatives 3 and 6) or of 3-oxo-butanoic and -pentanoic acid (16 and 23). The mechanism of the brominations is interpreted. The conversion of serine to enactiomcrically pure dioxanones 26-28 (Scheme 4) is also discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700423

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Addendum (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1229-1229

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19870700428

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Mitteilungen - Communications (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1230-1231

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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URL: http://dx.doi.org/10.1002/hlca.19870700429

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Enzyme-Catalyzed Hydrolysis of Some Functionalized Dimethyl MalonatesPresented at the meeting of the Swiss Chemical Society, Berne, October 10, 1986. (1987)

Luyten, Marcel ; Müller, Susanna ; Herzog, Beat ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1250-1254

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: A method is described for the preparation of (+)-(R)-methyl hydrogen 2-(tert-butoxymethyl)-2-methyl-malonate (5e) in synthetically useful amounts from readily available starting material.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700503

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Diels-Alder-Reaktionen von 2,4-Bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien mit HeterodienophilenTeil der geplanten Dissertation von U. R. [1]. (1987)

Ried, Walter ; Reiher, Uwe ; Jan, W. Bats

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1255-1260

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Source: Wiley InterScience Backfile Collection 1832-2000

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Description / Table of Contents: Diels-Alder Reactions of 2,4-Bis{[(tert-Butyl)dimethylsilyl]oxy}-3-aza--1,3-pentadien with HeterodienophilesThe 2,4-bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien(2) reacts via the Diels-Alder adducts 3, 6a-c, and 8a, b, which cannot be isolated, giving the triazines 4, 7a-c, and the oxadiazines 9a, b. The hydrolysis of 4 in MeOH affords the N-acetyl-acetamid derivative 5. The formula of 9a is proven by an X-ray-structure analysis.

Notes: No. Abstract.

Additional Material: 1 Ill.

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Zwei weitere Iridoid-glycoside und ein Monoterpen-glycosid aus Sambucus ebulus L. (Caprifloiaceae). 3. Mitteilung über die Inhaltsstoffe der Zwergholunderwurzel (1987)

Gross, Gian-Andrea ; Sticher, Otto ; Anklin, Clemens

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 91-101

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: New Iridoid Glycosides and a Monoterpene Glycoside from Sambucus ebulus L. (Caprifloiaceae)From the roots of Sambucus ebulus L., two novel valeriana-type ester iridoid glycosides, 6′-O-apiosylebuloside (1) and 7,7-O-dihydroebuloside (3), along with the open-chain monoterpene glycoside 5 were isolated. Their structure elucidation is based mainly on one- and two-dimensional NMR methods. 1H,1H-COSY experiments permitted complete assignment of signals arising from the disaccharide unit in 1. Biogenetically, 3 seems to represent the equivalent of loganin in the valeriana-type series of iridoid glycosides.

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700111

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Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin (1987)

Wolf, Jean-Pierre ; Pfander, Hanspeter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 116-120

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of ‘D-Isothreonine’ and ‘L-Alloisothreonine’ Starting from L-AlanineStarting from L-alanine, ‘D-isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L-alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700113

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Oxidative Breaking of Long-Chain Acetylenic Enol Ethers of Glycerol of the Marine Sponges Raspailia pumila and of Model Compounds with Aerial Oxygen (1987)

Guella, Graziano ; Mancini, Ines ; Pietra, Francesco

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1400-1411

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The raspailynes (novel long-chain enol ethers of glycerol having the enol ethers double bond conjugated in sequence, to an acetylenic and an olefinic bond, isolated from the North-East-Atlantic sponges Raspailia pumila and R. ramosa) are stable under normal hydrolytic conditions for enol ethers. In contrast, when their solutions are evaporated, these lipids such as raspailyne Bl (=(-))-3-[(1Z,5Z)-(tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(--2) rapidly react with aerial O2 under normal laboratory-daylight conditions, with rupture of the C=C enol ether bond to give 1-O-formylglycerol (3) and an aldehyde (such as tridec-4-en-2ynal(4) from (-)-2). This reaction must be caused by triplet O2, since thermally generated singlet O2 has no effect on (-)-2 in solution. That the mere presence of an enol-ether moiety conjugated to an acetylenic group is responsible for such a behaviour is demonstrated with the model compounds 1-methoxypentadec-1-en-3-yn-5-ol (6a) and its 5-O-acetyl or 5-O-tetra-hydropyranyl derivatives 6b and 6c, respectively. Resistance to both hydroytic conditions and singlet O2 of these compounds is thought to arise from electron depletion at the enol-ether C(beta;) atom by the acetylenic group. Plausible reaction pathways for enol-ether bond rupture in these compounds by aerial O2 are outlined.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700521

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Catalytic Intramolecular Palladium-Ene Reactions. Preliminay CommunicationPresented at the ‘4th IUPAC-Symposium on Organometallic Chemistry Directed towards Organic Synthesis’ (OMCOS IV), July 28, 1987, Vancouver, Canada. (1987)

Oppolzer, Wolfgang ; Gaudin, Jean-Marc

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1477-1481

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism (D → E → F, Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β-H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd (13 → 14 → 15).

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700604

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Drug-induced modifications of the immune response part 9Part8: [1]4-(Arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenylcycolopropyl)furan-3-carboxamides as Novel Antiallergic Compounds (1987)

Georgiev, Vassil St. ; Mack, Robert A. ; Walter, David J. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1526-1530

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Notes: The synthesis and antiallergic activity of a series of 4-(arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenyl-cyclopropyl)furan-3-carboxamides 10 are described. Treatment of N-substituted 2-amino-4,5-dihydro-4-oxofuran-3-carboxylic acids 9 with chlorooxobis(2-oxo-1,3-oxazolidin-3-yl)phosphorus (2) and an appropriate aromatic amine in the presence of Et3N, resulted in a novel 3(2H)-furanone-→2(5H)-furanone rearrangement that led to the facile preparation of the new amides 10. The latter exerted a potent antiallergic activity when tested in the dermal vascular permeability and active anaphylaxis assays in rats. The most active compound 10b inhibited the action of serotonin, histamine, and bradykinin by 94, 92, and 100%, respectively, when administered intraperitoneally to rats at doses of 100 mg/kg. The present series of 10 represents a novel class of antiallergic agents.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19870700609

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Notiz über die Verwendung von 3-(Arylsulfonyl)-2-cycloalkenonen als 2-Cycloalkinon-Synthese-Equivalente (1987)

Kienzle, Frank ; Minder, Rudolf E.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1537-1539

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Note on the Use of 3-(Arylsulfonyl)-2-cycloalkenones as Synthesis Equivalents of 2-Cycloalkynones3-(Arylsulfonyl)-2-cyclopentenones and 3-phenylsulfonyl-2-cyclohexnone undergo Diels-Alder reactions with cyclopentadiene. Elimination of arylsulfinic acid leads to products, which would have been obtained directly from a Diels-Alder reaction of 2-cyclopentynone or 2-cyclohexynone.

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URL: http://dx.doi.org/10.1002/hlca.19870700611

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Inhibition of Electron-Hole Recombination in Substitutionally Doped Colloidal Semiconductor Crystallites (1987)

Moser, Jacques ; Grätzel, Michael ; Gallay, Roland

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1596-1604

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The subtitutional doping of 120-Å- sized TiO2 Particles with Fe(III)ions has a profound effect on the charge carrier recombination time in this colloidal semiconductor. In undoped particles, the mean lifetime of an electronhole pair is ca. 30 ± 15 ns. Doping with 0.5% Fe(III) drastically augments the charge-carrier lifetime which is extended to minutes or hours. The slow character of the recombination dynamics in Fe(III)-doped colloids was confirmed by laser photolysis using the characteristic optical of electrons in TiO2 to monitor the time course of the reaction. EPR studies showed the Fe(III) ions to enter the host lattice on Ti(IV) sites, charge compensation taking place through the formation of oxygen vacancies. Valence-band holes produced under band-gap excitation react with these centers it the bulk forming Fe(IV), the conduction band electrons being trapped by Ti(IV) at the particle surface. Presumably, the spatial separation of the trapped electron and hole sites inhibits their recombination.

Additional Material: 7 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700617

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The Radical Anions of 1,2-diphenylcyclohexene and Structurally Related Compounds. Conformational ESR and ENDOR studies (1987)

Gerson, Fabian ; Martin, Williiam B.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1558-1568

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: ESR, ENDOR, and TRIPLE resonance studies have been performed on the radical anions of 1,2-diphenylcyclohex-1-ene (4), 1,2-di(perdeuteriophenyl)cyclohex-1-ene ((D10)4) the trans-configurated 3,4-diphenyl-8-oxabicyclo[4.3.0]non-3-ene (5) and its 2,2,5,5-tetradeuterio derivative (D4)5, and 2,3-diphenyl-8,9,10-trinorborn-2-ene (6). The spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} exhibit strong temperature dependence along with a specific broadening of ESR hyperfine lines and proton ENDOR signals. The coupling constant, which bears the main responsibility for these features, is that of the β-protons in the quasi-equatorial positions of the cyclohexene ring, and the experimental findings are readily rationlized in terms of relatively modest conformational changes without invoking the inversion of the half-chair form. The hyperfine data for the β-protons in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} closely resemble the corresponding low-temperature values for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document}, However, the ‘unusual’ features observed for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} are absent in the ESR and ENDOR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document}, because the half-chair conformation of the cyclohexene ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} is deprived of its flexibility. Although the boat form of this ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} is also rigid, the spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} are temperature-dependent, due to an interconversion between two propeller-like conformations of the phenyl groups. The pertinent barrier is 30 ± 5 kJ·mol-1. An analogous interconversion presumably takes place in \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} as well, but, unlike \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document}, it is not amenable to experimental study.

Additional Material: 7 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700614

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Synthesis and Formation of Ironcarbonyl Complexes of 3′,3′-Dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane]. Single-Crystal and Molecular Structure of syn,exo2,3-anti,endo5,6-trans-μ-[(1r,2r,3s,4s,5s,6r)-c,2,3,c-η:c,5,6,c-η-(3′,3′-dimethyl-2,3,5,6,-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane])]bis(tricarbonyliron)Interaction between non-conjugated chromophores, Part 27. Part 26, see [1]. (1987)

Rubello, Albino ; Vogel, Pierre ; Chapuis, Gervais

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1638-1648

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The 3′,3′-dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane] (3) was derived from 6,6-dimethylfulvene and maleic anhydride. Its reaction with 1 equiv. of ethylenetetracarbonitrile (TCNE) was not regioselective and gave a 1:1 mixture of the corresponding monoadducts 10 and 11. The rate constants of the Diels-Alder additions of 10 and 11 to TCNE were significantly smaller than that of the reaction 3 + TCNE. Monocomplexation of 3 with Fe2(CO)9 was highly exo-face selective giving a mixture of the corresponding monocomplexes 12(anti-exo) and 13(syn-exo). The latter were complexed with Fe2(CO)9 in a non-stereoselective fashion, giving mixtures of the dicomplexes 14(anti-exo, syn-endo), 15(anti-exo,syn-exo), and 16(anti-endo, syn-exo). Exchange of the CO ligands was a faster process for the endo-Fe(CO)3 moieties than for the exo-Fe(CO)3 moieties. Line-shape analysis of the 13C-NMR spectrum of 15 established that one of the exo-Fe(CO)3 groups in 15 rotates ca. 3 times as fast as the other Fe(CO)3 group at 40°. The structure of the anti-endo, syn-exo dicomplex 16 was determined by single-crystal X-ray diffraction studies.

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New Antifungal Chromenyl Ketones and their Pentacyclic Dimers from Hypericum revolutum VAHLPresented in part at the 34th Annual Congress on Medicinal Plant Research, Hamburg, FRG, 22-27 September, 1986. (1987)

Décostered, Laurent A. ; Hostettmann, Kurt ; Stoeckli-Evans, Helen ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1694-1702

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Two new 2H-1-benzopyranyl ketones 1 and 2 and three new pyrano[3,2-c: 4,5,6-d′ e′]di[1]benzopyrandiyl diketones 3, 4a/4b, and 5 have been isolated from the leaves and twigs of Hypericum revolutum VAHL (Guttiferae). The structure of 3 (hyperevoline) was established by X-ray analysis as 1,1′-[1,13,13a,13b-tetrahydro-5,8,10-trihydroxy-2,2,6,9,13,13-hexamethyl-2H, 7aH-pyrano[3,2-c:4,5,6-d′e′]di[1]benzopyran-4, 11-diyl]bis[2-methyl-1-propanone]. The structures of the isolated compounds were established by spectroscopic (UV, IR, EI-MS, 1H- and 13C-NMR) and chemical (acetylation and acidic dimerization) methods.

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Mammalian Alkaloids: Configurations of Optically Active Salsoline- and 3′,4′-Dideoxynorlaudanosoline-1-carboxylic AcidsSalsoline and norlaudanosoline are well known alkaloids, and these names will be used in the General Part (for systematic names, see Expert. Part). The systematic name for salsoline is 1-methyl-7-methoxy-1,2,3,4-tetrahydroisoquinolin-6-ol and that for norlaudanosoline, also named tetrahydropapaveroline, is 1-(3′,4′-dihydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol. (1987)

Chrzanowska, Maria ; Schönenberger, Bernhard ; Brossi, Arnold ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1721-1731

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of the optical isomers of (±)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate ((±)-2) was accomplished by reaction of (±)-2 with (+)-(R)-1-phenylethyl isocyanate, separation of the urea diastereoisomers (-)-4A and (+)-4B, and alcoholysis of the ureas in refluxing BuOH. Optically active isoquinoline-carboxylates 2A,B and hydantoins 8A,B isolated were characterized. The absolute configuration of the reaction products was established by X-ray analysis of the optically active hydantoin (+)-8A. Hydrolysis of the methyl isoquinolinecarboxylates 2A,B with 48% HBr soln. at reflux afforded the desired optically active 3′,4′-dideoxynorlaudanosoline-1-carboxylic acids 1A,B required for enzyme-inhibition studies. Details of the X-ray diffraction analysis of (+)-methyl salsoline-1-carboxylate hydrobromide ((+)-11A·HBr) prepared earlier are included. CD spectra of (+)-(S)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate hydrobromide ((+)-2A. HBr) and (-)-(R)-methyl salsoline-1-carboxylate hydrochloride ((-)-11B·HCl) confirmed the assignment of their (S)- and (R)-configurations, respectively.

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Determination of the Quantum Yield of Intersystem Crossing of Rose Bengal (1987)

Murasecco-Suardi, Patricia ; Gassmann, Ernst ; Braun, André M. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1760-1773

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (ϕet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · ϕet = Φ(1O2), with ϕet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2).

Additional Material: 8 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19870700712

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‘Face-to-Face’-Benzo-anellierte homologe Hypostrophene. Synthesen, Röntgenstrukturanalysen und PE-Spektren (1987)

Fessner, Wolf-Dieter ; Sedelmeier, Gottfried ; Knothe, Lothar ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1816-1842

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: ‘Face-to-Face’ Benzo-anellated Homologous Hypostrophenes. Syntheses, X-Ray-Structure Analyses and PE Spectra‘Face-to-face’ Benzo-anellated homologous hypostrophenes (series M), of interest as substrates for [6 + 6]-photocycloaddition reactions, have been synthesized. From X-ray structural analyses of 13b and 13c shortest C—C distances of 2.80(2.76)/2.71 Å and interorbital angles (ω) of 129° (128°)/130° between the benzene rings have been determined. The PE spectra are discussed in the context of transannular π,π interactions.

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URL: http://dx.doi.org/10.1002/hlca.19870700718

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Formation and Structure of the Phosphoranyl Radical Derived from 1,2-Phenylene Phosphorochloridate: a Solid-State ESR Study (1987)

Cattani-Lorente, Maria ; Bernardinelli, Gérald ; Geoffroy, Michel

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1897-1904

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The crystal structure of 1,2- phenylene phosphorochloridate has been determined. X-Ray irradiation of these crystals, at low temperature, leads to the formation of a radical exhibiting hyperfine structure with P and Cl nuclei. The corresponding ESR tensors are obtained, and they show that this radical is a phosphoranyl radical adopting a slightly distorded σ* structure. The same species could be produced in frozen solution, its hyperfine tensors are, then, more in accordance with a trigonal-bipyramid structure. The effects of the host matrix on the stabilization of the structure of phosphoranyl are investigated.

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URL: http://dx.doi.org/10.1002/hlca.19870700724

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Isolierung und Strukturaufklärung von 36 Diterpenoiden aus Trichomen von Plectranthus edulis (VATKE) T.T. AYE (1987)

Künzle, Josef Max ; Rüedi, Peter ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1911-1929

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Isolation and Structure Elucidation of 36 Diterpenoids from Leaf-Glands of Plectranthus edulis (VATKE) T.T. AYEAnalysis of the polar diterpenoids from the yellow glands of the title plant from Kenya and Abyssinia led to the identification of several novel abietanoids. Main compound is the known edulon A (40), a 5(4→3) abeo-abietane. Minor compounds include 6 different royleanones, 15 spirocoleons, 3 vinylogous quinones, 8 acylhydroquinones (as their 6,7-dioxo compounds or the tautomeric disophenols), 2 naphthaquinones (as the 1,10-seco-abietanoids), and deacetyledulon A. The known coleon-A-lactone (37) now has also been found in Plectranthus edulis. The intermediacy of the γ-enollactol 44, combined with a leaving group on C(3) is postulted to explain the biogenesis of the unusual 4H-5-oxaaceanthrylen skeleton of edulon A.

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Synthesis of trans-10,11-Dihydro-10,11-dihydroxy-5H-dibenz[b,f]azepine-5-carboxamide, a Major Metabolite of Carbamazepine (1987)

Heckendorn, Roland

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1955-1962

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The stereoselectivity of the reduction of 5-carbamoyl-10,11-dihydro-11-oxo-5H-dibenz[b,f]azepine-10-yl acetate (6), prepared in two steps from 10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide (4), has been studied. Among the reagents used, diisobutylaluminum hydride (DIBAH) was found to give the highest trans/cis diol ratio. This allowed the preparation of the important trans-diol metabolite 3 of carbamazepine (1).

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URL: http://dx.doi.org/10.1002/hlca.19870700730

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Are the known Δ2-cephems inactive as antibiotics because of an unfavourable steric orientation of their 4α-carboxylic group? Synthesis and biology of two Δ2-cephem-4β-carboxylic acids (1987)

Cohen, Nissim C. ; Ernest, Ivan ; Scartazzini, Riccardo ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1967-1979

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Two representatives of the yet unknown type of Δ2-cephem-4β-carboxylic acids were prepared. Contrarily to the prediction based on the activity model of Cohen, both acids proved inactive as antibiotics. Possible reasons for this discrepancy are briefly discussed.

Additional Material: 1 Ill.

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Isolierung von 10′-Apo-β-carotin-10′-ol und (3R)-10′-Apo-β-carotin-3,10′-diol (Galloxanthin) aus Rosenblüten. 5. Mitteilung über Rosenfarbstoffe1. bis 4. Mitt., s. [1-4]. (1987)

Märki-Fischer, Edith ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1988-1993

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Isolation of 10′-Apo-β-carotene-10′-ol and (3R)-10′-Apo-β-carotene-3,10′-diol (Galloxanthin) from Rose FlowersThe novel (all-E)-10′-apol-β-carotene-10′-ol (2) and (all-E,3R)-10′-apo-β-carotene-3,10′-diol (5) have been isolated from petals of one yellow species and various whitish or yellow blend varieties of rose cultivars. Each (all-E)-compound is accompanied by a (Z)-isomer, probably the (9Z)-isomer. Diol 5 proved to be identical with galloxanthin, an apo-10′-carotenol previously isolated from the retina of chicken.

Additional Material: 3 Ill.

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Nucleotides. Part XXVI.Part XXV: [1].. A new synthesis of 9-(′-D-ribofuranosyl)uric acid and its 5′-monophosphateDedicated to Professor Morio Ikehara, Osaka University, Osaka, Japan (1987)

Schulz, Bernd S. ; Pfleiderer, Wolfgang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 210-218

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Syntheses for 9-(β-D-ribofuranosyl)uric acid (16) and its 5′-monophosphate 14 have been achieved starting from guanosine and applying the 2-(p-nitrophenyl)ethyl group for protection of the aglycon moiety as well as the phosphate function. A more efficient and direct approach to 14 uses O6, O8-dibenzyl protection and phosphorylation by the Yoshikawa procedure. The various protected intermediates have been characterized by spectroscopic means and elemental analysis.

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URL: http://dx.doi.org/10.1002/hlca.19870700126

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Erratum (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 271-271

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19870700131

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Intramolecular Cyclizations of Allenic Acylureas and -Amides (1987)

Trifonov, Latchezar S. ; Orahovats, Alexander S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 262-270

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Keywords: Chemistry ; Organic Chemistry

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Notes: Allenic acids are found to add to dicyclohexylcarbodiimide affording, in the presence of Et2NH, the 4H-1,3-oxazin-4-ones 5 via 4. Under neutral conditions, they add to diaryl- or pyridyl(cyclohexyl)carbodiimides and triphenylketene imine to give the corresponding tricyclo[5.2.2.01,5]undeca-4,8,10-trien-3-ones 7, 8, 9, and 12. The allenic phenyl ester 13a dimerises, on heating in a [2+2] head-to-head fashion, to 14 but fails to undergo intramolecular Diels-Alder cyclization, to 15.

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Addition of Chiral Glycine, Methionine, and Vinylglycine Enolate Derivatives to Aldehydes and Ketones in the Preparation of Enantiomerically Pure α-Amino-β-Hydroxy Acids (1987)

Seebach, Dieter ; Juaristi, Eusebio ; Miller, David D. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 237-261

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Chiral enolates of imidazolidinones and oxazolidinones from the title amino acids react with carbonyl compounds to afford the corresponding alcohols in excellent yields (see Scheme 5). Furthermore, the addition to aldehydes proceeds with high diastereoselectivity to give, after acid hydrolysis, threo-α-amino-β-hydroxy acids of high enantiomeric purity. Some of the threo-α-amino-β-hydroxy acids prepared in this work are the proteinogenic (S)-threonine (26), the naturally occurring (S)-3-phenylserine (28), and (S)-3-hydroxyleucine (27) as well as the unnatural (S)-4,4,4-trifluorothreonine (30) and (S)-3-(4-pyridyl)serine (31). The N-methylamide of (2S,3R,4R,6E)-3-hydroxy-4-methyl-2-(methylamino)-6-octenoic acid (32), the unique amino acid in the immunosuppressive cyclosporine, was prepared by the new method. This report presents also information suggesting that both steric and stereoelectronic effects are responsible for the good stereoselectivities observed.

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Mitteilungen - Communications (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 272-274

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19870700132

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Masthead (1987)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

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URL: http://dx.doi.org/10.1002/hlca.19870700201

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Elektrochemische Oxidation von (S)-Äpfelsäure-Derivaten: ein Weg zu enantiomerenreinen alkylierten Malonaldehydsäure-estern (1987)

Renaud, Philippe ; Hürzeler, Marianne ; Seebach, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 292-298

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Electrochemical Oxidation of (S)-Malic-Acid Derivatives: a Route to Enantiomerically Pure Alkylmalonaldehydic EstersThe 3,3-dialkymalic-acid diesters, prepared by the previously described diastereoselective alkylations through dilithium alkoxide enolates, are saponified to the monoesters containing a free α-hydroxycarboxylic-acid moiety(Scheme 3). The monoesters are subjected to electrochemical oxidative decarboxylation in MeOH. If the intermediate monoacids are purified, the malonaldehydic esters (2-formy1-2-alkylcaroxylates) Obtained by this procedure are enantiomerically pure; they have the same structural features, i.e. two enantiotopic functionalized branches on the (persubstituted) stereogenic center, as the well known 3-hydroxy-2-methylpropanoic acid (‘Roche acid’) which was employed frequently as a starting material for the preparation of either enantiomer of various target molecules.

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Ringerweiterung unter Lactonisierung von methylierten 1-(3′-Hydroxypropyl)-2-oxocyclododecan-1-carbonitrilen (1987)

Milenkov, Branimir ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 308-314

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Notes: Ring Enlargement by Lactonization of Methylated 1-(3′-Hydroxypropy1)-2-oxocyclododecane-1-carbonitrilesThe title compounds were prepared by Michael reaction of 2-oxocyclododecane-1-carbonitrile (1) and acrylaldehyde and its derivatives followed by NaBH4 reduction or methylation of the aldehyde group with [(CH3)2Ti(i-PrO)2] (Scheme 1). In all cases, the ring enlargement was performed with Bu4NF/THF to give different methylated derivatives of 12-cyano-15-pentadecanolide (13) in 95-99% yield. The Yields of the rearrangement products are not dependent on the positions and numbers of the CH3 groups in the side chain of 3. The lactonization reaction is of unremarkable stereoselectivity.

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Neuartige Triterpen-Lactone aus Helenium autumnale L. (1987)

Matusch, Rudolf ; Häberlein, Hanns

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 342-346

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Notes: Novel Triterpene Lactones of Helenium autumnale L.Three novel triterpene lactones 1-3 could be detected by investigating a pentane extraxt of the Helenium autumnale L. (Asteraceae) roots. The structures are especially elucidated by 1H- and 13C-NMR spectroscopy. The lactones 1-3 formally represent Diels-Alder products of a reaction between a sesquiterpene lactone and an α,β-unsaturated sequiterpene aldehyde.

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URL: http://dx.doi.org/10.1002/hlca.19870700211

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Electrochemical Investigation of Potassium Heptacyanorhenate(III) in Aqueous Solution (1987)

Marty, Werner ; Renaud, Philippe ; Gampp, Harald

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 375-380

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Keywords: Chemistry ; Organic Chemistry

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Notes: The electrochemistry of potassium heptacyanorhenate(III) in aqueous solution was studied by cyclic and by rotating disk voltammetry at planar microelectrodes. The results are consistent with a single, reversible electron transfer: Re(CN)3-7 + e⇄Re(CN)4-7 with E′0 = 643 mV vs. NHE. A single protonation equilibrium is observed: Re(CN)4-7 + H+⇄ Re(CN)7H3- with pK = 1.31 determined from combined voltammetric and pH data. The Re-CN bond appears to be kinetically inert, and none of the cyano complexes in other oxidation states of Re claimed in the literature was found in the potential range - 2 V to + 1 V.

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URL: http://dx.doi.org/10.1002/hlca.19870700215

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Triaziridine 8. Mitteilung7. Mitteilung: [1].. Zur Acylierung Von Dialkyl-triaziridinen (1987)

Hilpert, Hans ; Hoesch, Lienhard ; Dreiding, André S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 390-395

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: On the Acylation of Dialkyl-triaziridines(2,3-trans)-Diisopropyl- (1) and (2,3-cis)-1,3-cyclopentylenetriaziridine (2) were reacted with ClCOOCH3. In the case of 1, with or without pyridine, an expected acylation at N(1) resulted in the methoxycarbonyl derivative 3. In the case of 2, the reaction in pyridine led to the γ- and α-dihydropyridyl derivatives 5 and 6, respectively, where the acylpyridinium moiety had become attached by a ring C-atom to N(1); without pyridine, it afforded the N-cyclopentenylcarbamates 13 and 14by opening of the triaziridine ring and loss of N2. The mechanisms proposed for these reactions involve the initial attack of an electrophile at N(1) of 1 but at N(2) (or N(3)) of 2. This difference is rationalized with steric factors, inasmuch as the hindrance to an attack at N(2) (or (3)) is greater in i than in 2, whereas this hindrance at N(1) is smaller in 1 than in 2. The greater resistance to opening of the saturated N3-homocycle during acylation of the monocyclic triaziridine 1, as compared to that of the tricyclic one 2, is attributed to greater strain in the latter system.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700217

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Asymmetric Diels-Alder Reactions of Cyclopentadiene with N-Crotonoyl- and N-Acryloyl-4,4-Dimethyl-1,3-Oxazolidin-2-one, Mediated by Chiral Lewis Acids (1987)

Chapuis, Christian ; Jurczak, Janusz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 436-440

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: One-pot Diels-Alder reactions of cyclopentadiene with 3-crotonoyl- (2) and 3-acryloyl-4,4-dimethyl-1,3-oxazolidin-2-one (3), Mediated by chiral Lewis acids, are described. AlCl3, EtAlCl2, Et2AlCl, TiCl4, ZrCl4, SnCl4, SiCl4, and BBr3, modified with derivatives of D-mannitol, L-tartaric acid, and (R)-binaphthol, were applied as chiral promotors. The reaction with dienophile 2, carried out in CH2Cl2 at -78° with high yield, was characterized by excellent π-face selectivity. In case of the reaction with dienophile 3, the efficiency of the chirality transfer was much lower.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700223

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Synthesis of the (+)-Enantiomer of Taonianone, a Furanoid Diterpene from Brown AlgaeDedicated to Prof. W.P. Neumann on the occasion of his 60th birthday (1987)

Huckestein, Martina ; Kreiser, Wolfgang ; Rüschenbaum, Volker

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 445-447

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The constitution and absolute configuration of the furanoditerpene taonianone (1) has been established by synthesis starting from (-)-carveol (2).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700225

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Copper and Silver Atoms in the β-Cage of a Zeolite: Model Calculations (1987)

Calzaferri, Gion ; Forss, Lars

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 465-479

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The electronic structures of the 4-4 SBU, the β-cage, and the β-cage with two 4-4 SBU's attached to it have been studied by means of EH-MO calculations. No indication of the formation of a band structure has been found. The HOMO region consists of many closely spaced, localized states, 98.6% of them concentrated on the O-atoms. Reversible color changes of Cu+1 and Ag+1 zeolites observed upon hydration-dehydration experiments can be understood as charge-transfer transitions from the HOMO concentrated on the zeolite O-atoms to the metal cations. As soon as the Cu+1 or Ag+1 are partially hydrated, the ns* and np* states are shifted to higher energies. The luminescence observed with dehydrated Cu+1-zeolites X is caused by a 4p*←HOMO absorption, followed by spontaneous 4s*←4p* emission. After a detailed study of a Cu+1 in the 6-6 SBU, we discuss the electronic structure of a β-cage filled with 1,2,4,8, and 9 Cu+1. In each case, the β-cage is found to be too small to allow the formation of a band structure. The levels caused by the added copper are distinctly quantized. Calculations on [Ag3(H2O)3]3+ in a β-cage are reported. The direct interaction between the Ag-atoms is significant. As a consequence, the states formed by Ag 5s and 5p atomic orbitals are delocalized over the three Ag-centers. In both the Cu+1 and the Ag+1 zeolites, the ligand-field picture is found to be insufficient to explain the electronic structure, when the metal is coordinated to the zeolite oxygen framework.

Additional Material: 12 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700227

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Complexes of 2,2′,2″-Nitrilotriphenol. Part 2. Crystal and Molecular Structures of Three Boron Complexes (1987)

Müller, Edgar ; Bürgi, Hans-Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 511-519

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Crystal and molecular structures of a complex between B(III) and the tripod ligand 2,2′,2″-nitrilotriphenol as well as of its pyridine and quinuclidine adducts are presented. The 2,2′,2″-nitrilotriphenyl borate (III) molecule shows a strained, tricyclic chelate system with a central N-B donor-acceptor bond of 1.681(5) Å. In the adducts with pyridine (IV) and quinuclidine (III-quin), this bond is broken, the N-atom inverts and is pushed out of the coordination sphere (B-Nintern = 2.82 Å for Py and 2.85 Å for quin), and a new bond is formed between the boron atom and the external nucleophile (B-Nextern = 1.631 Å for Py and 1.643 Å for quin).

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700304

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Angular Distortions at Tetracoordinate Carbon Planoid Configurations in Substituted Spiro[4.4]nonanesDedicated to Professor Albert Eschenmoser (1987)

Luef, Wolfgang ; Keese, Reinhart ; Bürgi, Hans-Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 534-542

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The configuration of the spiro centre in polycyclic compounds containing a spiro[4.4]nonane substructure is analyzed in terms of symmetry coordinates. As revealed by X-ray structures of such compounds, the local distortions around the quaternary C-atom are dominated by a decrease of the ring-bond angles at the spiro centre and a twist of one ring relative to the other. The planoid deformations given by the planarization index PC are comparatively small for spiro[4.4]nonanes, which contain either no additional bridges between the rings or only α,β′-or β,β′-polymethylene bridges. This indicates that the local strain in the spiro C(C)4 fragments is rather small.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700306

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Syntheses of Diamino-dideoxylyxose Derivatives using Acylnitroso DienophilesPresented at the ‘4th REGIO Symposium in Organic and Bioorganic Chemistry’, September 26-28, 1984, at Wintzfelden, France, which was organized by the Universities of Basel, Switzerland, of Freiburg i.Br., Germany, and of Mulhouse, France. For a preliminary communication, see [1]. (1987)

Defoin, Albert ; Fritz, Hans ; Schmidlin, Christian ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 554-569

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: N-Acylnitroso derivatives 6 which were prepared by in-situ oxidation of the corresponding hydroxamic acids 5 reacted instantaneously and in high yields with dihydropyridine 4. The Diels-Alder adducts 8 were formed regiospecifically with the acylnitroso dienophiles 6a-c, whereas the dienophiles 6d-f gave mixtures of both regioisomers 7 and 8. These and some other results [2] were best explained by the FMO theory. The Diels-Alder adducts 7 and 8 gave the corresponding ‘anti’-cis-glycols when reacted with OsO4/N-methylmorpholine N-oxide. Hydrogenolysis of the N-O bond followed by peracetylation led to the expected aminolyxose derivatives 14 and 16. A similar sequence, using 4 and the hydroxamic-acid derivative 18 of (+)-D-mandelic acid led, with a poor asymmetric induction, to a mixture of the expected optically active aminolyxose compounds 19A/19B.

Additional Material: 5 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19870700308

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