ZIB

101

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Bestimmung von Stabilitätskonstanten in Ethanol für Li+-selektive Ionophore mittels differentieller Dampfdruckosmometrie (1989)

Bliggensdorfer, René ; Suter, Gabriela ; Simon, Wilhelm

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1164-1168

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Determination of Stability Constants in Ethanol for Li+-selective Ionophores by Differential Vapour Pressure OsmometryStability constants of some neutral carriers and their bridged isologues in interaction with Li+ and Na+ are determined by a differential vapour pressure osmometry method in ethanol utilizing Bjerrum formation curves. All ionophores studied induce high Li+ selectivity in solvent polymeric membranes.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720535

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102

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Mitteilungen (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1170-1172

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720538

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103

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Masthead (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720601

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104

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Halochrome Molekeln 8. Mitteilung. Synthese und acidobasisches Verhalten von 3′-substituierten 6,11-Dihydrospiro[[1]benzopyrano[4,3-b]indol-6,9′-9′H-xanthenen] (1989)

Gunzenhauser, Sigmund ; Balli, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1186-1198

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Halochromic Molecules. Synthesis and Acidobasic Properties of 3′-substituted 6,11-dihydrospiro[[1]benzopyrano[4,3-b]indol-6,9′-9′9′H-xanthenes]We have synthesized a series of 3′-substituted 6,11-ihydrospiro[6H-chromeno[4,3-b]indol-6,9′-9′H-xanthenes] and one of their respective aza analogues. 1H-MR data as well as the fragmentation in the mass spectra of starting and final products supported the postulated structures. With acid, the spiro compounds form ring-opened intensely coloured xanthylium salts. UV/VIS spectra of these salts are listed and discussed. The ∊pH* curves in buffered MeOH/H2O solutions and the pK* values are determined. The title compounds could possibly be used in ‘pressure sensitive papers’.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720603

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105

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Cascade Reactions. A Simple One-pot Synthesis of the Mitomycin Skeleton (1989)

Defoin, Albert ; Geffroy, Guillaume ; Le Nouen, Didier ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1199-1215

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Nitroso-arene dienophiles 1 react regiospecifically with the conjugated dienals 2 and 3a/3b, and lead thereby to the unstable Diels-Alder cycloadducts 4 and 5. These undergo two types of cascade reactions which give pyridinium betaines 6 and pyrrolo-indoles 8 as the major reaction products. The one-pot syntheses of pyrroloindoles 8 represent a new and easy access to the basic skeleton of mitomycins 10. The scope and limitations of the cascade reactions were investigated.

Additional Material: 5 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720604

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106

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Corallistin A, a second example of a free porphyrin from a living organism. Isolation from the demosponge Corallistes sp. of the coral see and inhibition of abnormal cells (1989)

D'Ambrosio, Michele ; Guerriero, Antonio ; Debitus, Cécile ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1451-1454

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: It is shown that the demosponge Corallistes sp. (Tetractinomorpha, Lithistida, Corallistidae) collected in the Coral Sea, contains corallistin A (1), the second example, of a free porphyrin from a living organism. The compound proved to be active against the Kb cell line. In contrast with the geoporphyrins which do not bear any O-atom corallistin A (1) carries two carboxylic groups.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720704

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107

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New chromonocoumarin (=6H, 7H-[1]Benzopyrano[4,3-b][1]benzopyran-6,7-dione) derivatives from Polygala fruticosa BERG (1989)

Di Paolo, Ermindo R. ; Hamburger, Matthias O. ; Stoeckli-Evans, Helen ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1455-1462

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Three chromonocoumarins ( =6H, 7H-[1]benzopyrano[4,3-b][1]benzopyran-6,7-diones) 1-3 have been isolated from the leaves and the root bark of polygala fruticosa BERG. (syn. Polygala oppositifolia L.; Polygalaceae). The structure of frutinone A (1) was established by X-ray diffraction analysis. The structures of the previously undescribed compounds frutinone B (2) and C (3) were deduced by spectroscopic methods (EI-MS, UV, IR, 1H-and 13C-NMR, including NOE and COSY) in comparison with 1. Chromonocoumarins 1-3 are the first representatives of a new type of naturally occurring compounds. Frutinone A shows strong fungicidal activity against Cladosporium cucumerinum.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720705

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108

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Synthesis of hydroxy- and methoxy-substituted octahydrobenzo[g]isoquinolines as potential ligands for serotonin receptorsDedicated to Prof. C. Benezra on the occasion of his 50th birthday (1989)

Papageorgiou, Christos ; Petcher, Trevor J. ; Waldvogel, Erwin

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1463-1470

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: In 7 steps, 6- or 9-hydroxylated or -methoxylated trans-octahydrobenzo[g]isoquinolines were efficiently synthesized starling from dimethoxynaphtbalenes (Scheme), as potential new selective ligands for serotonin receptors. The 6-substituted compounds had very little affinity to common neurotransmitter receptors, with the exception of adrenergic α2. The 9-substituted compounds, while showing interesting affinity for 5HT1a receptors, had comparable affinities for adrenergic α1 and β2, and in one case for dopamine D2 receptors.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720706

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109

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Der Zugang zum Antitumor-Antibiotikum CC-1065 mittels Hetero-Cope-Umlagerung von Vinyl-N-phenylhydroxamaten (1989)

Martin, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1554-1582

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The Access to the Three Subunits of the Antitumor Antibiotic CC-1065 by Hetero-Cope Rearrangement of Vinyl N-Phenylhydroxamates.The use of the hetero-Cope rearrangement of vinyl N phenylhydroxamates to indoles for the preparation of the 1,2-dihydro-3H, 6H-benzo[1,2-b:4,3-b′]dipyrrole skeleton, the structural subunits characteristic of the antitu-mor antibiotic CC-1065 as well as the phosphodiesterase inhibitors PDE-I and PDE-II is described.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720717

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110

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New aromatic musk odorants: Design and synthesisDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)

Fehr, Charles ; Galindo, José ; Haubiichs, Rolf ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1537-1553

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: By appropriate structural modification of known musk odorants, new strong musk odorants have been discovered. Incorporation of supplementary CH3 or CH2 groups into the basic musk skeleton of type G only slightly modifies the global shape of the molecule but leads to densely packed structures of enhanced lipophilicity. For the construction of these highly substituted 1,2,3,4-tetrahydronaphthalenes, new annulation sequences (intramolecular mono- and dialkylations; see Schemes 3,6, and 8) have been developed and, in certain cases, the design of the target molecules was dictated by both structure-activity-relationship and synthetic considerations (e.g. 46 and 47, Scheme 6). This work also presents an original solution to an analytical problem: the distinction between a C2- and a Cs-symmetrical aromatic hydrocarbon (viz. 71 and 72) by conversion into a [Cr(CO)3arene]complex.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720716

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111

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Photochemistry of ethyl 2,3-dihydro-2,2-dimethyl-3-oxo-1H-pyrrole-1-carboxylateDedicated to Prof. Dr. W. Walter on the occasion of his 70th birthday (1989)

Patjens, Jan ; Margaretha, Paul

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1817-1824

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The title compound 7 is obtained by reductive dehalogenation from 4-bromo-2,3-dihydro-2,2. -dimethyl-3-oxo-1H-pyrrole-1-carboxylate (8) in 90% yield, Aza-enone 7 undergoes [2 + 2] cycloaddition from the triplet state with both electron-rich and electron-deficient alkenes. The behaviour of 7 in light-induced reactions is compared to those of 2,2-dimethyl-3(2H)-furanone (1a) and of the corresponding thiophenone 1b. In the photodimerization and the cycloaddition to either 2,3-dimethylbut-2-ene or to dimethyl maleate of these ketonic five-membered heterocycles with one heteroatom, the overall efficiency increases in going from the furan 1a to the thiophene 1b and to the pyrrole 7.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720818

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112

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Total synthesis of 2-(β-D-ribofuranosyl)thiazole-4-carboxamide (Tiazofurin) and of precursors of ribo-C-nucleosidesEnantiomerically pure 7-oxabicyclo[2.2.1]hept-5-en-2-yl derivatives (‘naked sugars’[1]) as synthetic intermediates, Part VIII. Part VII, see [2]. (1989)

Bimwala, R. Mampuya ; Vogel, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1825-1832

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: (1R,2S,4R)-2-Cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl (1S′)-camphanate (5) was transformed into (-)-methyl 2,5-anhydro-3,4,6-O-tris[(tert-butyl)dimethylsilyl]-D-allonate (2), (+)-1,3-diphenyl-2-{2′,3′,5′-O-tris[(tert-butyl)dimethylsilyl]-β-D-ribofuranosyl}imidazolidine (3), and the benzamide 20 of 1-amino-2,5-anhydro-1-deoxy-3,4,6-O-tris-[((tert-butyl)dimethylsily)]-D-allitol. Compound 2 was converted efficiently into optically active tiazofurin (1).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720819

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113

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The stereoselectivity of the alkylation of the dianion of ethyl 2-hydroxy-6-methylcyclohexanecarboxylates: Control of stereochemistry at three adjacent stereogenic centers (1989)

Fráter, Georg ; Günther, Wulf ; Müller, Urs

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1846-1851

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Yeast reduction of rac-ethyl 2-methyl-6-oxocylohexanecarboxylate (rac-1) yielded selectively (+)-ethyl 2-hydroxy-6-methylcyclohexane carboxylate (+)-2 (Scheme 1) which has been alkylated with 5-iodo-2-methylbut-2-ene by (the dianion method to furnish the 4-methylbut-3-enyl derivat 3 (Scheme 3)). NaBH4 reduction of (+)-1 led to three hydroxy-carboxylates (-)-2, (+)-5, and (-)-6 (Scheme 4). Allylation of the dianion of (+)-5 afforded (+)-7.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720821

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114

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Methyl-jasmonat: Ein kurzer Weg zum Naturstoff und seinem unnatürlichen Enantiomer via Palladium(0)-induzierte, enantiodivergente Alkylierung von Cyclopent-2-en-1,3-diol-Derivaten (1989)

Montforts, Franz-Peter ; Gesing-Zibulak, Ingrid ; Grammenos, Wassilios ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1852-1859

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Methyl Jasmonate: A Short Synthesis of Naturally Occurring Methyl Jasmonate and its Unnatural Enantiomer via Enantiodivergent Alkylation of Cyclopent-2-ene-1,3-diol Derivatives by Palladium(0)-Induced ReactionsPalladium-catalyzed alkylation of cyclopent-2-ene-1,2-diol derivatives like 2 is a useful method for enantiodivergent functionalization, resulting in both enantiomeric series of chiral building blocks. The chiral building blocks 3 and 13 can be transformed to methyl jasmonate (1)and its unnatural enantiomer ent-1, recent statement [1b] that 1 has no odour at all and that ‘methyl jasmonate's’ fragrance is actually due to its cis-isomer ent-11 has been confirmed also for the enantiomeric series.

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URL: http://dx.doi.org/10.1002/hlca.19890720822

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115

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New Cell Growth-Inhibitory Cyclohexadienone Derivatives from Hypericum calycinum L.Presented in part at the 36th Congress of the Society of Medicinal Plant Research, Freiburg im Breisgau, FRG, 12-16th September, 1988, and at the Meeting of the Swiss Chemical Society, Bern, 21st October, 1988 (1989)

Decosterd, Laurent A. ; Stoeckli-Evans, Helen ; Chapuis, Jean-Charles ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1833-1845

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The crude petroleum-ether extract of the aerial parts of Hypericum calycinum L. (Guttiferae) exhibited in vitro growth-inhibitory activity against the Co-115 human colon carcinoma cell line. Bioassay-guided fractionation of this extract allowed the isolation of the cyclohexadienone derivatives 1-5, four of which are previously undescribed compounds. The structures of the known chinesin II (1) and of 2 (hypercalin A) were established by 1H- and 13C-NMR spectroscopy and were confirmed by X-ray analysis of their crystalline mixture which revealed the complete relative configuration of both compounds. The structure of 3 (hypercalin B) was elucidated by means of extensive 1D- and 2D-NMR experiments, including DQ-COSY, HETCOR and LR-HETCOR. The structure of compound 4 (hypercalin C) was established by 1H- and 13C-NMR spectroscopy and confirmed by X-ray analysis to be the 3,5-dihydroxy-4-{[(1R*,2S*, 5S*)-2-hydroxy-2-methyl-5-(1-methylethenyl)cyclopentyl]methyl}-6,6-bis-(3-methylbut-2-enyl)-2-(2-methylpropanoyl)cyclohexa-2,4-dien-1-one. The structures of the higher isomeric homologues 5a/5b were deduced by comparison of their UV, 1H-, and 13C-NMR spectra with those of 4. The isolated compounds appeared to be related to chinesin I and II previously isolated from Hypericum chinense L. and were responsible for the growth-inhibitory activity of the extract against the Co-115 human carcinoma cell line. Moreover, 1/2 and 3 showed molluscicidal activity against the schistosomiasis-transmitting snail Biomphalaria glabrata.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720820

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116

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Mitteilungen (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1925-1925

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720824

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117

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Synthese und NMR-spektroskopische Charakterisierung neuer Adenin- und 6-ThioxopurincarboxamidineHerrn Prof. Dr. Wolfgang Hilger zum 60. Geburtstag mit den besten Wünschen gewidmet (1989)

Ried, Walter ; Woithe, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1860-1867

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis and NMR-Spectroscopic Characterization of New Adenine- and 6-ThioxopurinecarboxamidinesAdenine (1) or 1H-purine-6(7H)-thione (4) react with carboximidoyl chlorides 2 to yield the adenine-9-carboxamidines 3 or the 6,7-dihydro-6-thioxo-1H-purine-7-carboxamidines 5 and 6,9-dihydro-6-thioxo-1H-purine-9-carboxamidine 6 a, respectively. The structures of the compounds were determined by 1H- and 13C-NMR spectroscopy.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720823

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118

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New Triterpenoid N-Acetylglycosides with Molluscicidal Activity from Tetrapleura tetraptera TAUB (1989)

Maillard, Marc ; Hostettmann, Kurt ; Adewunmi, Clement O.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 668-674

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Activity-guided fractionation of the MeOH extract of the fruits of Tetrapleura tetraptera TAUB. (Mimosaceae) afforded 4 saponins 1-4, which exhibited strong molluscicidal properties against the schistosomiasis-transmitting snails Biomphalaria glabrata. Chemical, enzymatic, and spectral methods (DCI-MS, 1H-NMR, 13C-NMR) showed that they were N-acetylglycosides of oleanolic acid and of echinocystic acid. Apart from saponin 1 (aridanin), previously isolated from this plant, glycosides 2-4 are new naturally occurring compounds.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720407

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119

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Pteridines. Part XLIIPart XLI, see [1]. Synthesis and properties of 8-substituted 2,4-dithiolumazines (1989)

Hübsch, Walter ; Jibril, Ibrahim ; Huttner, Gottfried ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 744-755

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Condensation reactions of the 5-amino-6-(subst. amino)-2,4-dithiouracils 12 and 13 with diacetyl or benzil led to the 6,7,8-trisubstituted 2,4-dithiolumazines 14-16. Methylation of these compounds affected both thio functions forming various types of 2,4-bis(methylthio)lumazine derivatives depending on the nature of the substituents at C(7) and N(8). The 6,7,8-trimethyl-2,4-dithiolumazine (14) was converted into 7,8-dihydro-6,8-dimethyl-7-methylidene-2,4-bis(methylthio)pteridine (17), whereas the 8-methyl-6,7-diphenyl-(15) and the 8-(2-hydroxyethyl)-6,7-diphenyl-2,4-dithiolumazine (16) yielded the corresponding covalent inter- or intramolecular 7,8-adducts 18-21. The unusual structures were proven by spectroscopic means and those of the alcohol adducts 20 and 21, furthermore, confirmed by X-ray analysis.

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720415

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120

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A Novel Access to Ionone-Type Compounds: (E)-4-oxo-β-ionone and (E)Oxo-β-irone via metal-catalyzed intramolecular reactions of α-diazo ketones with furansDedicated to Dr. G. Ohloff the occasion of his 65th birthday (1989)

Wenkert, Ernest ; Decorzant, René ; Näf, Ferdinand

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 756-766

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: (E)-5-Demethyl-4-oxo-β-ionone (2), (E)-4-oxo-β-ionone (3), (E)-4-oxo-β-irone (4), and the five-membered ring analogs 36-41 were synthesized by a novel, convergent route starting from 2-methylfuran (1). A recently discovered, intramolecular reaction of 2-(diazoacyl)furans, catalyzed by dirhodium tetraacetate, leading to dienediones served as key step, thereby testing its utility in natural-product synthesis for the first time.

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URL: http://dx.doi.org/10.1002/hlca.19890720416

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121

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Mono- and Dialkylation of Derivatives of (1R, 2S)-2-Hydroxycyclopentanecarboxylic Acid and -cyclohexanecarboxylic acid via bicyclic dioxanones: Selective generation of three contiguous stereogenic centers on a cyclohexane ringPartially published in preliminary from [1] or mentioned in a previous paper [2]Dedicated to Dr. Günther Ohloff on the occasion of his 65th birthday (1989)

Herradón, Bernardo ; Seebach, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 690-714

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Ethyl (1R, 2S)-2-hydroxycyclopentanecarboxylate and -cyclohexanecarboxylate (1a and 2a, respectively) obtained in 40 and 70% yield by reduction of 3-oxocyclopentanecarboxylate and cyclohexanecarboxylate, respectively (Scheme 2), with non-fermenting yeast, are converted to bicyclic dioxanone derivatives 3 and 4 with formaldehyde, isobutyraldehyde, and pivalaldehyde (Scheme 3). The Li-enolates of these dioxanones are alkylated (→5a-5i, 5j, 6a-6g), hydroxyalkylated (→51, m, 6d, e), acylated (→5k, 6c) and phenylselenenylated (→7-9) with usually high yields and excellent diastereoselectivities (Scheme 3, Tables and 2). All the major isomers formed under kinetic control are shown to have cis-fused bicyclic structures. Oxidation of the seleno compounds 7-9 leads to α, β-unsaturated carbonyl derivatives 10-13 (Scheme 3) of which the products 12a-c with the C=C bond in the carbocyclic ring (exocyclic on the dioxanone ring) are most readily isolated (70-80% from the saturated precursors). Michael addition of Cu(I)-containing reagents to 12a-c and subsequent alkylations afford dioxanones 14a-i and 16a-d with trans-fused cyclohoxane ring (Scheme 4). All enolate alkylations are carried out in the presence of the cyclic urea DMPU as a cosolvent. The configuration of the products is established by NMR measurements and chemical correlation. Some of the products are converted to single isomers of monocyclic hydroxycyclopentane (17-19) and cyclohexane derivatives (20-23; Scheme 5). Possible uses of the described reactions for EPC synthesis are outlined. The observed steric course of the reactions is discussed and compared with that of analogous transformations of monocyclic and acyclic derivatives.

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Apparent Failure of the Wharton Rearrangement in a Tricyclo[7.1.1.02,7]undecaneDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)

Thomas, Alan F. ; Di Giorgio, Roberto ; Guntern, Olivier

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 767-773

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The Wharton rearrangement of 2,3-epoxytricyclo[7.1.1.02,7]undecan-3-one, a sterically hindered system, which should have led to an allyl alcohol with the OH group at a bridgehead, gave instead the allylically rearranged alcohol. The desired hydroxy compound was prepared by the Barton modification of the Wharton rearrangement: borohydride reduction to the epoxy alcohols, reaction with N, N′-thiocarbonylbisimidazole, and treatment with Bu3SnH. The bridgehead alcohol (and other 2-oxygenated tricyclo[7.1.1.02,7]undecanes) readily rearranged under acidic or thermal conditions.

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2′-Deoxy-β-D-ribofuranosides of N6-Methylated 7-Deazaadenine and 8-Aza-7-deazaadenine: Solid-phase synthesis of oligodeoxyribonucleotides and properties of self-complementary duplexes (1989)

Seela, Frank ; Kaiser, Klaus ; Bindig, Uwe

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 868-881

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The syntheses of 7-deaza-N6-methyladenine N9-(2′-deoxy-β-D-ribofuranoside) (2) as well as of 8-aza-7-deaza-N6-methyladenine N8- and N9-(2′-deoxyribofuranosides) (3 and 4, resp.) are described. A 4,4′-dimeth-oxylritylation followed by phosphitylation yielded the methyl phosphoramidites 12-14. They were employed together with the phosphoramidite of 2′-deoxy-N6v-methyladenosine (15) in automated solid-phase oligonucleotide synthesis. Alternating or palindromic oligonucleotides derived from d(A-T)6 or d(A-T-G-C-A-G-A*-T-C-T-G-C-A) but containing one methylated pyrrolo[2,3-d]pyrimidine or pyrazolo[3,4-d]pyrimidine moiety in place of a N6-methylaminopurine (A*) were synthesized. Melting experiments showed that duplex destabilization induced by a N6-Me group of 2′-deoxy-N6-methyladenosine is reversed by incorporation of 8-aza-7-deaza-2′-deoxy-N6-meihyladenosine, whereas 7-deaza-2′-deoxy-N6-methyladenostne decreased the Tm value further. Regiospecific phosphodiester hydrolysis of d(A-T-G-C-A-G-m6A-T-C-T-G1-C-A) by the endodeoxyribonuclease Dpn I, yielding d(A-T-G-C-A-G-m6A) and d(pT-C-T-G-C-A), was prevented when the residue c7m6Ad (2), c7m6z8Ad (3), or c7m6z8Ad′ (4) replaced m6Ad (1) indicating that N(7) of N6-methyladenine is a proton-acceptor site for the endodeoxyribonuclease.

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Acid-Catalyzed Rearrangement of 3-Aza-8-oxatricyclo[3.2.1. 02,4]octan-6-one Acetals. Highly Stereoselective Total Synthesis of 3-Amino-3-deoxy-D-altrose and DerivativesEnantiomerically pure 7-oxabicyclo[2.2.1]hept-5-en-2-yl derivatives (‘naked sugars’ [3]) as synthetic intermediates, Part VII. Part VI, see [l], Part V, see [2].For a preliminary communication, see [4]. (1989)

Nativi, Cristina ; Reymond, Jean-Louis ; Vogel, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 882-891

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Notes: Ethyl and tert-butyl azidoformate added to 7-oxabicyclo[2.2.1]hept-5-en-2-one dimethyl (5) and dibenzyl (6) acetals to give mixtures of regioisomeric triazolines. The latter gave the corresponding aziridines (6,6-dialkoxy-3-aza-8-oxatricyclo[3.2.1.02,4]octane-3-carboxylates 15, 19, 23, and 27 and 31) on UV irradiation. In the presence of protic acids, the aziridines were rearranged into protected amines ([3-endo-alkoxy-5-oxo-7-oxabicyclo[2.2.1]hept-2-exo-yl]carbamates 16, 20, 24, and 28 and 33). Using (+)-(1R, 4R)-5,5-bis(benzyloxy)7-oxabicyclo[2.2.1]hept-2-ene((+)-6) derived from furan and l-cyanovinyl (1S)-camphanate, the method was applied to prepare 2-O-benzyl-3-[(tert-butoxy)carbonyiamino]-5-O-(3-chlorobenzoyl)-3-deoxy-β-D-altrofuranurono-6,1-lactone ((-)-37). This compound was converted to methyl 3-amino-3-deoxy-α-D-altropyranoside hydrochloride (44) and several derivatives.

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A Regioselective Cyclohexannulation Procedure via Dienamine [4 + 2] Cycloaddition. Synthesis of Functionalised DecalinsDr. G. Ohloff on the occasion of his 65th birthday (1989)

Snowden, Roger L. ; Linder, Simon M. ; Wüst, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 892-905

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A regioselective cyclohexannulation procedure, whose key step involves the [4 + 2] cycloaddition of dienamines 12-24 with methyl acrylate, allows the conversion of cycloalkanones 1-11 to bicyclic dienoates 25 - 37. The chemistry of 26 is briefly examined and, in the context of organoleptic studies concerning functionalised 5,5,9-tri-methyldecalins, the transformation of 37 to ketones 44 and 46 as well as to acetates 53-56 is described.

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Biologically Active Natural Acetylenic Compounds from Eutypa lata (Pers: F.) TUL (1989)

Renaud, Jean-Marc ; Tsoupras, Georges ; Tabacchi, Raffaele

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 929-932

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Eight new acetylenic compounds have been isolated and identified from the culture medium of the fungus Eutypa lata. Structural elucidation and biological activity are discussed.

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Verschiedenartige Addukte von Ketonen, Diazocyaniden sowie Nitrosobenzol an (Methylidenamino)phospheneHerrn Prof. Dr. Hansgeorg Gareis zum60. Geburtstag gewidmet (1989)

Ried, Walter ; Fulde, Maria ; Bats, Jan W.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 969-974

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Notes: Various Adducts from Ketones, Diazocyanides, and Nitrosobenzene with (Methylidenamino)phosphines(Methylidenamino)phosphine 1a reacts with activated ketones to 2,7-dioxa-5-aza-1λ5-phosphabicyclo-[3.2.0]heptanes 2a, b and with nitrosobenzene to l, 3,5,2λ5-oxadiazaphosphole 3a. The reaction of 1b with nitrosobenzene and diethyl mesoxalate yields 2,7-dioxa-3,5-diaza-1λ5-phosphabicyclo[3.2.0]heptane 4. With the cyano group of diazocyanides, 1a reacts to the adducts 5a-d. The structure of 5a is proven by an X-ray diffraction analysis.

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Photochemical Synthesis of Cyclic 2-(2,2-Dimethylpropylidene)-1,3-dicarbonyl Compounds (1989)

Hobel, Klaus ; Margaretha, Paul

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 975-979

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Notes: Photolysis (λ = 254 nm) of 4-(t-Bu)-substituted [b]-fused bi- and tricyclic pyrandiones 5 affords title compounds 4 in good yields as well as small amounts of spiroalkanediones 8. The alkyl-substitution pattern at C(4) of the pyran ring in 5 determines the relative amount of α vs. β-cleavage products obtained from the primarily formed acyl-vinyloxy biradical.

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Silicon-Directed Regio- and Enantioselective Synthesis of α-Hydroxy-ketones Preliminary CommunicationDr. G. Ohloff on the occasion of his 65th Birthday (1989)

Lohray, Braj B. ; Enders, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 980-984

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Notes: α-Silylated ketones (S)-2 (ee ≥ 98%), easily available through silylation or silylation/alkylation from ketones 1 using the (-)-(S)-1-amino-2-(methoxymethyl)pyrrolidine (SAMP)-/(+)-(R)-1-amino-2-(methoxymethyl)pyrrolidine (RAMP)-hydrazone method, are oxidized to give α-hydroxy-ketones (R)-5 of high enantiomeric purity (ee ≥ 98%) and in good overall yields (51-70%). The key step of the procedure is the silicon-directed diastereoselective oxidation of the corresponding silyl enol ethers of (S)-2, with m-chloroperbenzoic acid or 3-phenyl-2-(phenylsulfonyl)oxaziridine, followed by flash chromatography and desilylation.

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A New Route to Crystalline Salts of the Hydrolytic Dimer of Chromium(III) (1989)

Merakis, Thomas ; Murphy, Annette ; Spiccia, Leone ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 993-995

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Crystalline salts of the hydrolytic dimer of Cr(III), [Cr2(μ-OH)2(H2O)8]X4·n H2O (X = p-toluenesulfonate (tos) or mesitylene-2-sulfonate (dmtos)) have been prepared in good yields via a simple two-step procedure: H+ oxidation of Cr metal to give Cr2+ (T ≍ 70°) followed by O2 oxidation, of Cr2+ to give the dimer (T ≍ 25°). The mechanism of conversion of Cr2+ into the dimer is discussed.

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Notiz über Ellagitannine und Flavonol-glycoside aus Rosenblüten10. Mitt. über Rosenfarbstoffe. 9. Mitt. S. [1], 8. Mitt. s. [2]. (1989)

Nayeshiro, Kyosuke ; Eugster, Conrad Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 985-992

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Note on Ellagitannins and Flavonol Glycosides from Rose PetalsPetals from two garden roses proved to be very rich in ellagitannins and flavonol glycosides. Rutin (1), spiraeoside (2), quercitrin (3), isoquercitrin (4), nicotiflorin (5), eugeniin (6), rugosin A (7), rugosin D (10), casuarictin (8), and tellimagrandin I (9) were isolated. Spiraeoside, at physiological pH, exerts a pronounced stabilisation of the anthocyanin colour with enhancement of extinction and bathochromic shift of the absorption maximum in the visible range. The abundance of gallic-acid derivatives 6-10 is in contrast to the apparent inability of rose flowers to produce anthocyanins with a trihydroxylated ring B, a prerequisite in breeding true blue-coloured roses.

Additional Material: 2 Ill.

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The Synthesis of Racemic Ambrox®Dedicated to Dr. Günther Ohloff on the occasion of his 65th birthday (1989)

Büchi, George ; Wüest, Hans

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 996-1000

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: (±)-Ambrox (10), the racemic form of (-)-Ambrox®, the commercially most important ambergris odorant has been synthesized from a readily available bicyclic keto ester in five steps. The racemic ether retains the characteristic scent of fine-quality ambergis, and the odor threshold of the racemate and the (-)-enantiomer prepared from natural sclareol were found to be essentially identical.

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Novel Prenylated Xanthones from Garcinia gerrardii HARVEY (1989)

Sordat-Diserens, Isabelle ; Marston, Andrew ; Hamburger, Matthias ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1001-1007

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Three novel prenylated xanthones, 1-3, have been isolated from the root bark of Garcinia gerrardii HARVEY ex T. R. SIM (G. natalensis SCHLECHTER; G. transvaalensis BURTT DAVY; Guttiferae). Structure elucidation was achieved by a combination of one- and two-dimensional NMR spectroscopic techniques, including long-range HETCOR, mass spectroscopy, and chemical methods. Garcigerrin A (1) and B (2) are pyrano derivatives of 3. They all show a rare 1,4,5 oxygenation pattern of the xanthone nucleus. Xanthone 3 is fungicidal against Cladosporium cucumerinum.

Additional Material: 1 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720518

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An Unexpected Asymmetric Reduction of 4-(1-Nitro-2-oxocyclododecyl)butan-2-one. Determination of the absolute configuration of (-)-15-hexadecanolide (1989)

Stanchev, Stephan ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1052-1060

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Reduction of the carbonyl group in the side chain of 4-(1-nitro-2-oxocyclododecyl)butan-2-one (3) with organoboron complexes are influenced by the chiral center, in 4-position with respect to the carbonyl C-atom, to which the NO2 group is attached, a rare type for an asymmetric reduction. Independent of the (R)- or (S)-configuration of the Alpine-Hydride, (+)-3 is reduced only to the (15S)-nitrolactone (+)-5 and, after subsequent transformations, to (+)-(-S)-15-hexadecanolide ((+)-1), enantiomer of the naturally occurring (-)-1.

Additional Material: 1 Ill.

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Synthèse du virensate de méthyle (1989)

Pulgarin, César ; Tabacchi, Raffaele

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1061-1065

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of Methyl VirensateThe synthesis of methyl virensate (=methyl 4-formyl-3,8-dihydroxy-1,6,9-trimethyl-11-oxo-11H-dibenzo-[b, e][1,4]dioxepin-7-carboxylate; 18) by the condensation of the substituted β-orcinol and orcinol units 9 and 10 followed by formylation and demethylation of the depsidone 13 is described.

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Synthesis of Polyaza Macrocyclic Ligands Incorporating Pyridine Units (1989)

Hosseini, Mir Wais ; Comarmond, Jacques ; Lehn, Jean-Marie

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1066-1077

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The synthesis of nine macrocyclic polyamines 2-10 containing pyridine units is described. These compounds are 22- (9), 24- (2-4,6,8,10), or 26- (5, 7) membered hexaaza (2,3,9,10) or octaaza (4-7) macrocycles in which one to four pyridine units are incorporated. Compounds 3,4,9, and 10 are homoditopic ligands, whereas 2 and 5 are heteroditopic and 6-8 multitopic receptors. Compounds 2-10 are potential ligands for metal cations as well as, in their protonated forms, for anions. Protonated macrocycles 2-10 are also potential catalysts for the hydrolysis of nucleotides and polyphosphates.

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URL: http://dx.doi.org/10.1002/hlca.19890720525

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Synthesis and Biological Evaluation of 14-Alkoxymorphinans Part 4Part 3:[1]. opioid agonists and partial opioid agonists in a series of N-(cyclobutylmethyl)-14-methoxymorphinan-6-ones (1989)

Schmidhammer, Helmut ; Burkard, Willy P. ; Eggstein-Aeppli, Lislott

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1233-1240

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The N-(cyclobutylmethyl)morphinans 12, 19, 20, 21, 27, and 29 and the N-(2-cyanoethyl) analogue 33 were prepared from different precursors. Pharmacological evaluation (e.g. opioid receptor binding assays, acetic-acid writhing test, hot-plate assay) points to a partial opioid agonism of compounds 12, 27, 29, and 33, and to full opioid agonism of compounds 19-21.

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URL: http://dx.doi.org/10.1002/hlca.19890720607

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Synthèse énantiospécifique de la (+)-(R)-éthyl-6-dihydro-2,3-méthyl-2-4H-pyranone-4, phéromone de la mite Hepialus hecta L (1989)

Deschenaux, Pierre-François ; Kallimopoulos, Thomas ; Jacot-Guillarmod, André

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1259-1261

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Enantiospecific Synthesis of (+)-(R)-6-Ethyl-2,3-dihydro-2-methyl-4H-pyran-4-one, Sex-pheromonal Component of the Male Swift Moth Hepialus hecta L.A new synthesis of (+)-(R)-6-ethyl-2,3-dihydro-2-methyl-4H-pyran-4-one ((R)-8), sex-pheromonal component of the male swift moth Hepialus hecta L., has been performed from (-)-(R)-1-(1,3-dithian-2-yl)propan-2-ol with an enantiomeric excess of ≥ 97%.

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A Novel Allenic Epoxycyclohexane and Related Compounds from Eutypa lata (Pers: F.) Tul (1989)

Renaud, Jean-Marc ; Tsoupras, Georges ; Stoeckli-Evans, Helen ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1262-1267

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The novel allenic epoxycyclohexanes 1, and related compounds 2 and 3 have been isolated from the culture medium of Eutypa lata. Their structures were established by combination of spectroscopic and chemical techniques. Biogenetic origin and biological activity of these compounds are also discussed.

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Metal Complexes with Macrocyclic Ligands Part XXXPart XXIX, see [1]. Synthesis and structure of halocuprates of tetraprotonated 1,4,8,11-tetraazacyclotetradecane and its Cu2+ complex (1989)

Studer, Martin ; Riesen, Andreas ; Kaden, Thomas A.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1253-1258

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: By mixing acidic solutions of 1,4,8,11-tetraazacyclotetradecane (Cy) with CuX2 (X = Cl-, Br-), either the hexahalocuprates of the tetraprotonated form of the macrocycle ([CyH4] [CuX6]) or the tetrahalocuprates of its Cu2+ complex ([CuCy] [CuX4]) are obtained. The structures of the chloro derivatives are established by X-ray diffraction analysis. In [CyH4] [CuCl6], the Cu2+ is in a tetragonally distorted octahedral geometry with four short and two long Cu—Cl bonds. The tetraprotonated macrocycle is centrosymmetric, and its conformation is exodentate, so that the four ammonium groups are as far as possible from each other to minimize the electrostatic repulsion. In [CuCy] [CuCl4], the Cu2+ ion complexed by the macrocycle is surrounded by four N-atoms in a square-planar arrangement. In addition, the axial positions are occupied by two Cl- ions of two CuCl42- units, which act as bridges. The macrocycle is in the trans-III-configuration. The other Cu2+ ion is coordinated by four Cl- ions in a distorted tetrahedral geometry. IR and VIS spectra of the chloro and bromo derivatives are used to discuss the structure of the bromo species.

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720610

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Synthesis of an N-Acetylated Heparin Pentasaccharide and its anticoagulant activity in comparison with the heparin pentasaccharide with high anti-factor-Xa activity (1989)

Peter Wessel, Hans ; Labler, Ludvik ; Tschopp, Thomas B.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1268-1277

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of tri-N-acetylated heparin pentasaccharide 2 is described. It was assembled from five suitably blocked monosaccharide units (3-7). Glucuronic-acid building block 4 was prepared from glucose by direct Jones oxidation of the 6-O-trityl derivative 18. The resulting acid 16 was esterified to 17 in large mounts using methyl chloroformate/base. Trimethylsilyl bromide proved to be an excellent reagent for the hydrolysis of a prop-1-enyl glycoside (19 →21). The pentasaccharide 29 was obtained by a [2 + 2] + 1 synthesis, the glycosylation reactions furnished good to very good yields. The identity of protected oligosaccharides was confirmed by 1H-NMR spectroscopy. Sequential deblocking of the pentasaccharide, O-sulfation, and N-acetylation gave 2 which was shown to exhibit ca. 600 times lower anticoagulant activity than pentasaccharide 1.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720613

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Ring-opened analogues of Ambrox®: Synthesis and Structure-Odour relationshipsDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)

Winter, Beat

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1278-1283

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Eight bicyclic ether derivatives 11-18, related to the tricyclic odorant Ambrox® (1) and its analogues 2-6 by formal heteroring-opening, have been prepared; their odoriferous activity/in activity is correlated with the steric accessibility of the ether O-atom, calculated by computer-aided molecular modeling.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720614

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Synthèse énantiospécifique du (-)-(1R, 3R, 5S)-diméthyl-1,3-dioxa-2,9-bicyclo[3.3.1]nonane (1989)

Masoni, Claudio ; Deschenaux, Pierre-François ; Kallimopoulos, Thomas ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1284-1287

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Enantiospecific Synthesis of (-)-(1R, 3R, 5S)-1,3-Dimethyl-2,9-dioxabicyclo[3.3.1]nonaneThe isomer (-)-(1R, 3R, 5S)-endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane ((1R, 3R, 5S)-8) has been synthesized from (-)-(3R)-methyl 3-hydroxybutanoate. The key intermediate (3R, 5R)-5 is proved to be a useful synthon for EPC syntheses.

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URL: http://dx.doi.org/10.1002/hlca.19890720615

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Separation of enantiomeric algal pheromones and related hydrocarbons by gas-liquid Chromatography on Modified Cyclodextrins as Chiral Stationary Phases. Biosynthetic relevance of racemic by-products (1989)

Boland, Wilhelm ; König, Wilfried A. ; Krebber, Ralph ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1288-1292

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The separation of the enantiomers of the olefinic hydrocarbons multifidene 3 and aucantene 5 from the pheromone blend of the two seaweeds Cutleria multifida and Chorda tomentosa is achieved by gas chromatography on modified cyclodextrins as chiral stationary phases. The method is also applicable for the separation of enantiomeric alkyl-, alkenyl- or alkynyl-substituted cyclooctadienes and cyclopentenes. A plausible rational is presented for the biosynthesis of racemic by-products of algal pheromone blends.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720616

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Herstellung substituierter 1,6-Methano[10]annulene durch Cycloadditionsreaktionen des 1H-Cyclopropabenzols (1989)

Neidlein, Richard ; Kohl, Matthias ; Kramer, Walter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1311-1318

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of Substituted 1,6-Methano[10]annulenes by Cycloadditions of 1H-CyclopropabenzeneDiels-Alder reactions of 1H-cyclopropabenzene (1) with electron-poor dienes, leading to substituted 1,6-methano[10]annulenes, are described.

Additional Material: 3 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720619

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Ethylene Biosynthesis part 10Part 9:[1]. Synthesis and study of racemic, (1R, 2S)-, and (1S, 2R)-1-Amino-2-(hydroxymethyl)cyclopropanecarboxylic Acid (1989)

Pirrung, Michael C. ; Dunlap, Steven E. ; Trinks, Uwe P.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1301-1310

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The preparation of optically active 1-amino-2-(hydroxymethyl)cyclopropanecarboxylic acid has been achieved by a route involving cycloalkylation of dimethyl malonate with epichlorohydrin and subsequent Hofmann rearrangement. The reaction of epichlorohydrin with nucleophiles may occur al either electrophilic site, epoxide or halide. Based on the absolute configuration of the starting materials and the lactones obtained, it has been shown that the initial step of the cycloalkylation occurs at the epoxide moiety. The 1-amino-2-(hydroxymethyl)-cyclopropanecarboxylic acid, an analogue of the precursor to the plant growth hormone ethylene, is to be used in affinity purification techniques and in generation of antibodies.

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URL: http://dx.doi.org/10.1002/hlca.19890720618

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Transition-metal complexes with bidentate ligands spanning trans-positions. Part XVIIIPart XVII: [1]. Crystal and molecular structure of the ligands 2,11-bis(di-R-phosphinomethyl)benzo[c]phenanthrene (R = Phenyl, tert-Butyl) and a comparison of their conformation in a variety of complexes (1989)

Bürgi, Hans-Beat ; Murray-Rust, Judith ; Camalli, Mercedes ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1293-1300

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The X-ray crystal structures of 2,11-bis(di-R-phosphinomethyl)benzo[c]phenanthrenes (R = Ph, t-Bu) are reported. Both ligands have the same conformation and the substitution of a Ph by a t-Bu group does not cause significant changes in the tetracyclic aromatic unit which shows the same distortions as the parent hydrocarbon. The conformations and structural features of the two ligands and 18 complexes containing these ligands as well as of one compound with a ligand with Et substituents are compared. It is pointed out that (1) the conformations of the free ligands differ significantly from those of their complexes, (2) in all the complexes characterized to date, these ligands act as chelating agents, and (3) the ligands adopt two different conformations in the complexes, one of them appearing to be more flexible than the other.

Additional Material: 4 Ill.

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Solid-phase Synthesis of C-Terminal Peptide Amino Alcohols (1989)

Neugebauer, Witold ; Escher, Emanuel

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1319-1323

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The solid-phase syntheses of enkephalin and somatostatin analogues with C-terminal OH functions instead of the normal carboxylates are described. The OH function of the N-terminal amino alcohol was acylated with succinic acid and esterified to the solid support. Normal Boc-TFA solid-phase strategy can be applied to build up and cleave these peptides. The succinic ‘handle’ can be removed by mild basic hydrolysis after cleavage.

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URL: http://dx.doi.org/10.1002/hlca.19890720620

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Festkörper-Polymerisation eines ‘Push-Pull’-Diacetylens23. Mitteilung über Aminoacryl-Derivate. 22. Mitteilung: [1]. (1989)

Galli, Roberto ; Neuenschwander, Markus ; Engel, Peter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1324-1336

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Solid-State Polymerisation of a ‘Push-Pull’-DiacetyleneSolid-state polymerisation of ‘push-pull’-diacetylene 5-(diphenylamino)-1-phenylpenta-2,4-diyn-1-one (1d), initiated by heating of crystals of 1d at 90°, gives ‘push-pull’ poly-diacetylene 2d. X-Ray results and spectroscopic data of monomer 1d as well as of polymer 2d are discussed.

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URL: http://dx.doi.org/10.1002/hlca.19890720621

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Asymmetric Induction on Copper(I) Chloride catalyzed 1,4-addition of alkylmagnesium chlorides to α, β-disubstituted (E)-enoylsultams and subsequent protonation (1989)

Oppolzer, Wolfgang ; Kingma, Arend J.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1337-1345

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Successive treatment of conjugated N-enoylsultams 2 with alkyl Grignard reagents/CuCl and aq. NH4Cl solution generated selectively two stereogenic centers at C(α) and C(β) providing, after flash chromatography and crystallization, acylsultams 5 in high purity. Mild cleavage afforded the recovered sultam auxiliary 1 and enantiomerically pure carboxylic acids 7.

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URL: http://dx.doi.org/10.1002/hlca.19890720622

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Nucleotides part XXXPartXXIX, see[1]. Chemical synthesis of adenylyl-(2′ → 5′)-adenylyl-(2′ → 5′)-8-azidoadenosine, and activation and photoaffinity labelling of RNase L by [32P]p5′A2′p5′A2′p5′N38A (1989)

Charubala, Ramamurthy ; Pfleiderer, Wolfgang ; Sobol, Robert W. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1354-1361

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The chemical synthesis of adenylyl-(2′-5′)-adenylyl-(2′-5′)-8-azidoadenosine (15) was performed by the phosphotriester approach. Enzymatic phosphorylation of 15 by [γ-32P]ATP led to the corresponding labelled 5′-monophosphate 16. Photoinsertion of 16 took place on UV irradiation by covalent cross linking to a protein of Mr 80 K known to be RNase L. Radiobinding and core-cellulose assays as well as photoaffinity labelling experiments with 16 are described.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720624

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Structure and Thermal Behaviour of Methylcyclopentadiene DimersDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)

Thommen, Walter ; Pamingle, Hervé ; Schulte-Elte, Karl H.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1346-1353

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The mixture of isomeric dimethyl-endo-tricyclo[5.2.1.02,6]deca-3,8-dienes (A) resulting from Diels-Alder reactions of 1-, 2-, and 5-methylcyclopenta-1,3-dienes (i-iii, respectively) at 20° was shown by GLC analysis to consist of at least 10 components (Table 1). The structures of the six major isomers 1-6, representing 96% of the total mixture, were established by 1H- and 13C-NMR spectroscopy. Whereas on heating up to 110° the proportions of 1, 2, 4, and 6 remain nearly unaffected (±2 %), the dimers 3 and 5, formed in 22 % and 24 % yield, respectively, at 20°, isomerise above 70° reversibly via [3,3]-sigmatropic rearrangement and equilibrate at 110° to a ca. 10:1 ratio.

Additional Material: 3 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720623

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Synthesis of cis and trans Whisky and Cognac lactones by the regiocontrolled alkylation of 2-(trimethylsiloxy)furan (1989)

Jefford, Charles W. ; Sledeski, Adam W. ; Boukouvalas, John

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1362-1370

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The racemic cis- and trans-5-butyltetrahydro-4-methylfuran-2-ones ( = whisky lactones) and their higher homologues tetrahydro-4-methyl-5-pentylfuran-2-ones ( = cognac lactones) have been prepared in 2-3 steps from 2-(trimethylsiloxy)furan. Regioselective alkylation of the latter afforded the 5-butyl- and 5-pentylfuran-2(5H)-ones which served as precursors for the stereocontrolled construction of either diastereoisomer of the beverage lactones. The structure and tautomerization of the diazomethane adducts of these 5-alkylfuran-2(5H)-ones are also described.

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Tilcotil® Studies [3+2] additions with isothiazol-3(2H)-one 1,1-dioxide (1989)

Burri, Kaspar F.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1416-1427

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Derivatives of isothiazol-3(2H)-one 1,1-dioxide react regiospecifically with 1,3-dipolar agents. The main regiocontrolling factor is ascertained to be the C=O group of the dipolarophile. The topology of the adducts is also in general agreement with predictions based on perturbation theory. Several adducts can be aromatized to heterocyclic equivalents of saccharin, and may then be elaborated into structural analogs of tenoxicam (Tilcotil® and piroxicam (Feldene®)).

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URL: http://dx.doi.org/10.1002/hlca.19890720630

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Mitteilungen (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1435-1437

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720632

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Masthead (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989)

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720701

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Application of the gold(I)-Catalyzed aldol reaction to a stereoselective synthesis of (2S, 3R, 4R, 6E)-3-Hydroxy-4-methyl-2-(methylamino)oct-6-enoic Acid ( = MeBmt(4R)-4-[(E)-But-2-enyl]-4, N-dimethyl-L-threonine = MeBmt (IUPAC/IUB three-letter amino-acid notation)), Cyclosporin's unusual amino acid (1989)

Togni, Antonio ; Pastor, Stephen D. ; Rihs, Grety

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1471-1478

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The title compound 8 was prepared in three steps starting from the optically pure aldehyde (2R, 4E)-2-methyl-hex-4-enal (3), thus constituting the shortest synthetic approach reported. Two of the three stereogenic centers in the product were generated in a coupling reaction of 3 with ethyl isocyanoacetate, catalyzed by a gold(I)/chiral ferrocenylphosphine system, giving the dihydrooxazole 5 in 85% diastereoselectivity (mismatchedcase). The weak effect of double stereodifferentiation in this reaction (matched case 90% ds) is discussed. N-Methylation and hydrolytic ring opening of 5 gave the protected form 7 of MeBmt, The X-ray diffraction study carried out on 7 confirms the absolute configuration of the two stereogenic centers formed in the gold(I)-catalytic reaction.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720707

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Catalytic effect of tetrabutylammonium fluoride in the preparation of secoribo-nucleosides (1989)

Hakimelahi, Gholam H. ; Khalafi-Nezhad, Ali

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1495-1500

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: A general and rapid procedure is developed for the preparation of secoribo-nucleoside analogues. Bu4NF has a marked effect on the condensation of guanine (5) with 2-(chloromethoxy)ethyl benzoate (2) or 1-halo-2-(chloromethoxy)ethanes 12 and 16. Condensation and deprotection of the acyl protecting group and nucleophilic displacement of the halogen atoms to yield 9-[(2-hydroxyethoxy)methyl] guanine (9) occurred in one step.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720710

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Interaction between the buffer Tris and the eu(III) ion: Luminescence and potentiometric investigationAbstracted, in part, from the Ph.D, Thesis of J.-M.P. (1989)

Pfefferlé, Jean-Marc ; Bünzli, Jean-Claude G.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1487-1494

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The interaction between the buffer 2-amino-2-(hydroxymethyl)propane-1,3-diol (Tris) and the Eu(III) ion has been studied by luminescence spectroscopy in D2O. Emission and excitation spectra (5D0←7F0 transition) indicate an interaction with both [TrisH]+ and neutral Tris species. The former is weak and probably of the outer-sphere type. The latter is of inner-sphere type and corresponds to the formation of the [Eu(Tris)]3+ species (estimated logK1 = 2.3 ± 0.3). Buffer Tris is also demonstrated to prevent the formation of an Eu-hydroxo species in the pD range of 7-8. Potentiometric measurements in H2O allowed a more precise calculation of the stability constant: logK1 = 2.44 ± 0.07. Comparison with the data for aliphatic amines and other metal ions lead to the conclusion that the Eu/Tris interaction is mainly achieved through the amino group. 1H-NMR spectra in presence of Tb(III) ions confirmed both this assumption and the presence of a weak interaction with TrisH+. Quantitative determinations of association constants between lanthanide ions and macromolecules of biological interest performed in presence of Tris should, therefore, be corrected for the Eu/Tris interaction.

Additional Material: 5 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720709

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Synthesis of(+)-(2S, 6S)-trans-α-Irone and of(-)-(2S, 6S)-trans-γ-IronePresented by D. Helmlinger at the meeting of the swiss chemical society, Bern, October 18th, 1985. (1989)

Helmlinger, Daniel ; Fráter, Georg

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1515-1521

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A 3:1 mixture of (+)-(2S, 6S)-trans-α-irone ((+)-1) and (-)-(2S, 6S)-trans-γ-irone (-)-2) has been synthesized with ca. 70% e. e. by the ene reaction of (-)-(S)-3 and but-3-yn-2-one.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720713

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Synthesis of 8-Aza-2′-deoxyadenosine and related 7-Amino-3H-1,2,3-triazolo[4,5-d]pyrimidine 2′-Deoxyribofuranosides: Stereoselective glycosylation via the nucleobase anion (1989)

Kazimierczuk, Zygmunt ; Binding, Uwe ; Seela, Frank

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1527-1536

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of 8-aza-2′-deoxyadenosine ( = 7-amino-3H-1,2,3 triazolo[4,5-d]pyrimidine N3-(2′-deoxy-β-D-ribofuranoside); 1) as well as the N2- and N1-(2′-deoxy-β-D-ribofuranosides) 2 and 3 is described. Glycosylation of the anion of 7-amino-3H-1,2,3-triazolo[4,5-d]pyrimidine (6) in DMF yielded three regioisomeric protected 2′-deoxy-β-D-ribofuranosides, i.e. the N3-, N2-, and N4-glycosylated isomers 7 (14%), 9 (11%), and 11 (3%), respectively, together with nearly equal amounts of their α-D-anomers 8 (13%), 10 (12%), and 12 (4%; Scheme 1). The reaction became Stereoselective for the β-D-nucleosides if the anion of 7-methoxy-3H-1,2,3-triazolo[4,5-d]pyrimidine (13) was glycosylated in MeCN: only the N3-, N2, and N1-(2′-deoxy-β-D-nucleosides) 14 (29%), 15 (32%), and 16 (23%), respectively, were formed (Scheme 2). NH3 Treatment of the methoxynucleosides 14-16 afforded the aminonucleosides 1-3. The anomeric configuration as well as the position of glycosylation were determined by combination of 13C-NMR, 1H-NMR, and 1D-NOE difference spectroscopy. Compound 1 proved to be a substrate for adenosine deaminase, whereas the regioisomers 2 and 3 were not deaminated.

Additional Material: 3 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720715

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Strukturaufklärung von N6-, 9- und 7-Acyladeninen durch 1H-und 13C-NMR-Spektroskopie von Festkörpern und in Lösung (1989)

Ried, Walter ; Woithe, Heinz ; Müller, Arndt

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1597-1607

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Structure Determination of N6-, 9-and 7-Acyladenines by 1H- and 13C-NMR Spectroscopy of Solids and in Solution.Adenine (1) reacts with carboxylic acid anhydrides or chlorides 2 to yield the acyladenine isomers 3-5. The isomeric structures were determined by 33C- and 1H-NMR spectroscopy in solution and by solid-state 13C-NMR spectroscopy.

Additional Material: 6 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720720

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Synthesis of cycloproparenes via aromatization of 7-Oxanorbornenes with Low-Valent titanium (1989)

Müller, Paul ; Schaller, Jean-Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1608-1617

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 1H-Cyclopropa[b]naphthalene 3c and the 2,7-diphenyl-substituted derivative 3a have been synthesized via cycloaddition of the appropriate isobenzofurans 1a and 1b to 1-bromo-2-chlorocyclopropene and aromatization of the adducts with low-valent Ti. The same procedure afforded the 2,7-dimethyl-H-cyelopropa[g]isoquinoline (15), but failed for the parent azacompound. Reaction of adducts of furans to 1-bromo-2-chlorocyclopropenes with low-valent Ti produced mixtures of cyclopropabenzenes 19 and 1,6-dihalogeno-1,3,5-cycloheptatrienes 18. The latter could be converted to cyclopropabenzenes with BuLi.

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Novel cembranolides (Coralloidolide D and E) and a 3,7-Cyclized cembranolide (Coralloidolide C) from the mediterranean coral Alcyonium coralloides (1989)

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

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1590-1596

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The Mediterranean alcyonacean Alcyonium (= Parerytkropodium) coralhides (PALLAS, 1766) is shown to contain three novel diterpenes which are of biogenetic significance: the 3,7-cyclized cembranoid Coralloidolide C ( = (+)-(6R*, 7R*, 11S*, 12aS* 3aE)-7,8-epoxy-3,5,6,7,8,9,10,11,12,12a-decahydro-12a-hydroxy-11-isopropenyl-1,4-dimethyl-3-oxocyciopentacydoundecene-8,6-carbolactone; (-)-3), the O-bridged diketonic cembranolide Coralloidolide D (= (+)-(1R*, 2S*, 3R*, 5R*, 12S*, 8Z)-2,5-epoxy-1-hydroxy-12-isopropenyl-5,9-dimethyl-7,10-dioxocyclotetradeca-8-ene-1,3-carbolactone; (+)-4), and the diketonic epoxycembranolide coralloidolide E (=(+)-(1R*, 2R*, 3R*, 12S*, 5Z, 8Z)-1,2-epoxy-12-isopropenyl-5,9-dimethyl-7,10-dioxocyclotetra-deca-5,8-diene-1,3-carbolactone; (+)-5), The latter in pyridine at r. t. undergoes a double bond shift from C(4) = C(5) to C(4) = C(18) to give the isomer (-)-7. Structural assignments are mainly based on ID and 2D NMR and MS spectral data. Either corailoidolide A ((-)-1) or the hypothetic unsaturated 1,4-diketone 9 can be envisaged as the precursors of all coralloidolides.

Additional Material: 2 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720719

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Aromatization of tetrahydrocyclopropa[a]naphthalenes: An alternative synthesis of 1H-Cyclopropa[a]naphthalene (1989)

Müller, Paul ; Bernardinelli, GéRald ; Thi, Huong Can Godoy-Nguyen

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1627-1638

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: 1H-Cyclopropa[a]naphthalene (1a) is accessible via reduction of the dichloro compound 1c with LiAlH4/AlCl3. Several derivatives of tetrahydrocyclopropa[a]naphthalene were synthesized. However, contrary to their 1,1-dihalogeno analogues, they afforded no cycloproparenes upon attempted aromatization.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720723

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Tricarbonyl-chromium complexes of benzannelated cycloproparenes (1989)

Müller, Paul ; Bernardinelli, Gérald ; Jacquier, Yvan ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1618-1626

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Reaction of 1H-cyclopropa [b]naphthalene (1a) or 1H-cyclopropa[b]anthracene (10a) with tris(acetonitrile)tricarbonylchromium affords cyclobutanaphthalenone and cyclobutaanthracenone 2 and 11, respectively. In contrast, the bis-silylated Cycloproparenes 1b and 10b undergo complexation at the terminal benzene ring and lead to the arene-tricarbonylchromium complexes 4b and 12, respectively. Desifylation of 4b to 4a is effected by t-BuOK.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720722

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Substituenteneffekte auf die NMR-Spektren von Pentafulvenen57. Mitteilung äber Fulvene, Fulvalene; 56. Mitteilung: [1].. (13C, 13C)-NMR-Kopplungskonstanten (1J(C, C)) (1989)

Bircher, Hansruedi ; Neuenschwander, Markus

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1697-1703

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Substituent Effects on NMR Spectra of Pentafulvenes. 13C, 13C-NMR Coupling Constants (1J(C, C))1H- and 13C-NMR spectra of 6-monosubstituted pentafulvenes 1-8 have been analysed, and 1J(C, C) coupling constants have been determined from ID-inadequate spectra of 13C satellites. It turns out that 13C,13C coupling constants of the ring C-atoms, and especially J(1,2)/J(3,4) and J(2,3), reflect the extent of π delocalisation in the fulvene ring. With increasing electron-donating capacity of the substituent R, J(1,2)/J(3,4) values are decreasing, while J(2,3) (and J(1,5)/J(4,5) as well) are increasing, and linear correlations of Hammett substituent constants σ+ and 1J(C,C) values are obtained.

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Thermal Valence Rearrangements of Heterocycles. Part 2. A new synthetic approach towards the indole ring system (1989)

Bennett, Grace A. ; Mullen, George B. ; Georgiev, Vassil St.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1718-1721

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: A new synthetic approach towards the indole ring system is described. When dimethyl 1-methyl-2-oxa-1-aza-spiro[4.5]dec-3-ene-3,4-dicarboxylate (6) was refluxed in toluene, the previously known dimethyl 4,5,6,7-tetra-hydro-1-methyl-1H-indole-2,3-dicarboxylate (7) was obtained in 71% yield, via a 2,3-dihydroisoxazole-pyrrole rearrangement. After treatment with DDQ, the tetrahydro analogue 7 was converted to the corresponding dimethyl 1-methyl-1H-indole-2,3-dicarboxylate (8).

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Nucleotides. Part. XXXIIPart XXXI: [1].. Synthesis of 2′-5′ Connected oligonucleotides. Prodrugs for antiviral and antitumoral nucleosides (1989)

Herdewijn, Piet ; Charubala, Ramamurthy ; De Clercq, Erik ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1739-1748

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The cytotoxically and antivirally active compounds bvUd (1), flUd (4), acyclovir (7), and Aa (12) have chemically been combined with the appropriately protected (2′-5′)diadenylate 20 by the phosphotriester approach to give the 2′-5′ oligonucleotide trimers 21-24. The deprotection of the various blocking groups by chemical means afforded the 2′-5′ trimers 25-28, which can be regarded as new type of a potential prodrug form delivering nucleotides to the targets inside cells. In an analogous series of reactions, 9-(3′-azido-3′-deoxy-β-D-xylofuranosyl)adenine was coupled with 7 to the 2′-5′ trimer 31. The antiviral screening of the oligonucleotides 25-27 and 31 showed biological activities closely related to the parent nucleosides, possibly indicating their release by enzymatic cleavage of the oligomers.

Additional Material: 1 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720811

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A Short, Simple Synthesis of (±)-Monomorine (1989)

Jefford, Charles W. ; Tang, Qian ; Zaslona, Alexander

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1749-1752

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Racemic monomorine (12) is prepared in six steps in 26% overall yield from 2-butyl-1H-pyrrole and ethyl (E)-but-2-enoate by exploiting the rhodium(II)-acetate-catalyzed decomposition of (4RS)-4-(2′-butyl-1′ H-pyrrol-1′-yl)-1-diazopentan-2-one (7).

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URL: http://dx.doi.org/10.1002/hlca.19890720812

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The Photochemical Synthesis and Denitrogenation of 8,9-diazadibenzo[c, e]isobullvalene (1989)

Burger, Ulrich ; Mentha, Yves G. ; Millasson, Patricia ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1722-1728

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Starting from dibenzo[a, c]cyclooctene (4) and 4-methyl-3H-1,2,4-triazol-3,5(4H)-dione (MTAD), the strained skeleton of the title azo compound 1 is assembled in a tandem photo-Diels-Alder addition/di-π-methane rearrangement sequence. The synthesis is completed by a stepwise hydrolytic oxidation of the ensuing triazolidine-dione 2 with nickel peroxide. Thermolysis of 1 in benzene solution is shown to be governed by an initial 1,3-dipolar cycloreversion which leads, via an intermediate diazo compound 11, to cyclobuta[1]phenanthrene 8 and two further carbene-derived C16H12 products. Photolysis of 1 at 350 nm leads in modest yield (12%), via a diazenyl diradical, to an unstable bridged bicyclobutane 10 (dibenzooctavalene). MNDO calculations suggest the latter to have a rapidly inverting, twisted structure of C2 symmetry.

Additional Material: 1 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720809

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Allobetonicoside and 6-O-Acetylmioporoside: Two new iridoid glycosides from Betonica officinalis L.Dedicated to Prof. Robert Hegnauer on the occasion of his 70th birthday (1989)

Jeker, Marianne ; Sticher, Otto ; Çaliş, İhsan ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1787-1791

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: A new allose-containing iridoid diglycoside, allobetonicoside (1), and a new acyl iridoid glucoside, 6-O-acetylmioporoside (2) have been isolated from the aerial parts of Betonica officinalis L. in addition to two known iridoid glucosides, acetylharpagide (3) and reptoside (4). Their structures have been determined by spectroscopic methods as well as by means of chemical evidence.

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URL: http://dx.doi.org/10.1002/hlca.19890720814

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Synthesis, Reactivity, and Application as Chiral Auxiliaries of the novel (3R)- and (3S)-4,5-dihydro-3-hydroxy-4,4,5,5-tetramethyl-3-phenylfuran-2(3H)-ones in the Paterno-Büchi reaction (1989)

Oppenländer, Thomas ; Schönholzer, Peter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1792-1800

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Both enantiomers of the novel α-hydroxy-γ -lactone (±)-3 (4,5-dihydro-3-hydroxy-4,4,5,5-tetramethyl-3-phenylfuran-2(3H)-one) have been synthesized via hydrolysis of the oxetanes 2 derived from the photochemical [2 + 2] cycloaddition of the ketones 1 and 2,3-dimethylbut-2-ene (Paterno-Büchi reaction) involving conventional separation of diastereoisomers (Schemes 2 and 3). The absolute configuration of (R)- and (S)-3 and of the corresponding oxetane precursors could be assigned on the basis of an X-ray structural analysis of the (-)-(1S, 4R)-camphanoyl derivative (3′S)-5 of (S)-3. O-Acylation of (S)-and (±)-3 to yield a variety of derivatives ((3′S)- and (3′RS)-5, (S)- and (±)-7, (±)-8, (±)-9) was accomplished by deprotonation with BuLi at room temperature and subsequent quenching of the Li alcoholate with acyl chlorides or acid anhydrides, demonstrating the extraordinary chemical stability of 3. Additionally, the course of the temperature-dependent diastereoselective Paterno-Büchi reaction of 2,3-dimethylbut-2-ene to the benzoylformate (S)-7 ( = (S)-1d; obtained from (S)-3) was shown to proceed with 58% de at 60°, leading to a decrease of enantiomeric purity in the hydrolysis product 3.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720815

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Tordanone, un stéroïde replié avec une jonction de cycle A/B β-cis (5β) et B/C α-cis(8α) (1989)

Haag, Thierry ; Hetru, Charles ; Luu, Bang

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1809-1816

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Tordanone, a Twice Bent Steroid Structure with Ring A/B β-cis(5β)- and Ring B/C α-cis(8α)-FusedThe 3β, 14α, 25-trihydroxy-5β, 8α-cholestan-6-one ( = tordanone; 4) has been prepared by stereospecific hydrogenation of 3β, 14α, 25-trihydroxy-5β-cholesta-7,22ξ-dien-6-one (5). This is the first stereospecific synthesis of a B/C cis-fused steroid belonging to the 5β, 8α -cholestane group with a H-atom at positions 5β (A/B cis-fused) and 8α. The resulting twice bent structure shows a particularly strong steric hindrance of the β-face where CH3(18) at the C/D ring junction and Hβ—C(7) of the B ring are very close to each other. Structural features and mechanistic aspects of the hydrogenation are discussed.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720817

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Synthese von (+)-Aspicilin mit Bausteinen aus nachwachsenden RohstoffenAus den Dissertationen oder der Diplomarbeit von E. F. [1], P. E. [2] oder D. N. [3].Die im Allgemeinen Teil verwendete Numerierung der C-Gerüste bezieht sich jeweils auf diejenige der Zielverbindung 1 (s. Formelbild von 1 in Schema 1).In dieser Mitteilung werden folgende Abkürzungen verwendet: 9-BBN: 9-Borabicyclo[3.3.1]nonan, COD: Cycloocta-1,5-dien, DBU: 1,8-Diazabicyclo[5.4.0]undec-7-en, DMAP: 4-(Dimethylamino)pyridin, MCPBA: m-Chloroperbenzoesäure, MEM: (2-Methoxyethoxy)methyl, NBS: N-Bromosuccinimid, NOE: ‘nuclear Overhauser enhancement’, PPTS: Pyridinium-p-toluolsulfonat, (+)-Pr-(hfc)3: Tris[3-(heptafluoropropyl-l-hydroxymethylen)-(+)-campherato]praseodym(III), TBAF: Tetrabutylammonium-fluorid, TBDMS: (tert-Butyl)dimethylsilyl, THP: Tetrahydropyran-2-yl, TMEDA: N, N, N′, N′-Tetramethylethylendiamin. (1989)

Quinkert, Gerhard ; Fernholz, Erhard ; Eckes, Peter ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1753-1786

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of (+)-Aspicilin Using Building Blocks from Renewable ResourcesThe 18-membered lichen macrolide (+)-aspicilin (1) is easily built up from compounds 14, 16, 3, and 24 following the C3 + C7 + C6 + C2 = C18 pattern (see Schemes). The synthesis requires 15 steps and gives 1 in 13% overall yield from D-mannose (2). The latter compound provides the stereogenic centers C(4), C(5), and C(6). The stereogenic center C(17) is supplied by building block 14 (from (-)-(S)-ethyl lactate).

Additional Material: 3 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720813

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Variable-Temperature and Variable-Pressure Kinetic and Equilibrium studies of formation and dissociation of [V(H2O)5NCS]2+ (1989)

Sauvageat, Pierre-Yves ; Ducommun, Yves ; Merbach, André E.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1801-1808

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The kinetics of formation and dissociation of [V(H2O)5NCS]2+ have been studied, as a function of excess metal-ion concentration, temperature, and pressure, by the stopped-flow technique. The thermodynamic stability of the complex was also determined spectrophotometrically. The kinetic and equilibrium data were submitted to a combined analysis. The rate constants and activation parameters for the formation (f) and dissociation (r) of the complex are: kf298/M-1 · S-1 = 126.4, kr298/s-1 = 0.82; ΔHf≠ /kJ · mol-1 = 49.1, ΔHr≠/kJ · mol-1 = 60.6; ΔSf≠/ J·K-1·mol-1= -39.8, ΔSr≠J·K-1·mol-1 = -43.4; ΔVf≠/cm3·mol-1 = -9.4, and ΔVr≠/cm3 · mol-1 =-17.9. The equilibrium constant for the formation of the monoisothiocynato complex is K298/M-1 = 152.9, and the enthalpy and entropy of reaction are ΔH0/kJ · mol-1 = - 11.4 and ΔS0/J. K-1mol-1 = +3.6. The reaction volume is ΔV0/cm3· mol-1 = +8.5. The activation parameters for the complex-formation step are similar to those for the water exchange on [V(H2O)6]3+ obtained previously by NMR techniques. The activation volumes for the two processes are consistent with an associative interchange, Ia, mechanism.

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URL: http://dx.doi.org/10.1002/hlca.19890720816

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Isotope Effects on the Lipophilicity of Deuterated CaffeinesPresented in part at the Third International Symposium on the Synthesis and Application of Isotopically Labelled Compounds, Innsbruck, July 17-21, 1988. (1989)

Bechalany, Antoine ; El Tayar, Nabil ; Carrupt, Pierre-Alain ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 472-476

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: In the present study, it is confirmed that the deuteration of C—H groups is accompanied by a small but genuine decrease in lipophilicity. The lipophilicity of deuterated isotopomers of caffeine was measured by reversed-phase HPLC. Overall, lipophilicity was shown to decrease when going from unlabelled caffeine to the three isomeric trideuterated caffeines, then to the three isomeric hexadeuterated caffeines, and finally to nonadeuterated caffeine. In addition, position-specific effects were also proven. E.g. (7-methyl-2H3)caffeine experienced a smaller isotope effect than its two positional isomers. Both a cavity factor (decreased volume of deuterated isotopomers) and intramolecular electronic effects are postulated to operate.

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URL: http://dx.doi.org/10.1002/hlca.19890720308

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Stereoselectivity in Reactions of Metal Complexes. Part XIPart X, see [1]. 2,6-Bis(pyrrolidin-2-yl)pyridine: Synthesis and resolution of the meso and the optically active isomers. Complex formation with copper(II) ion in aqueous solution (1989)

Bernauer, Klaus ; Gretillat, François

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 477-481

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The new linear triamine 2,6-bis(pyrrolidin-2-yl)pyridine (II) has been synthesized, and the (R, S)-, (R, R)-, and (S, S)-isomers have been separated. Compared to other triamines showing a similar structure, these new ligands form very stable Cu2+ complexes. No significant difference is observed between the meso and the racemic forms for their binary or ternary mixed-ligand complexes with the amino acids alanine and proline.

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URL: http://dx.doi.org/10.1002/hlca.19890720309

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Direct Formation of a Substituted [5.5.5.5]Fenestrane by Intramolecular Arene-Olefin Photocycloaddition (1989)

Mani, Jürg ; Schüttel, Stefan ; Zhang, Cong ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 487-495

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: In a search for further synthetic routes to substituted [5.5.5.5] fenestranes, compound 1a, a derivative of 7-methoxyindane, was photolyzed. Two of the three photoproducts, viz. the [3.5.5.5]fenestrane 3a and the isomer 4a, are formed according to the expected intramolecular meta-cycloaddition. A different mechanism is suggested for the formation of the major component 2a.

Additional Material: 4 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720311

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Synthese von (R)-β, β-Carotin-2-ol und (2R, 2′R)-β, β-Carotin-2,2′-diol (1989)

Gut, Samuel ; Wolleb, Heinz ; Pfander, Hanspeter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 496-501

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Description / Table of Contents: Synthesis of (R)-β, β-Caroten-2-ol and (2R, 2′R)-β, β-Carotene-2,2′-diolStarting from geraniol, the two carotenoids (R)-β, β-caroten-2-ol (1) and (2R, 2′R)-β, β-carotene-2,2′-diol (3) were synthesized. The optically active cyclic building block was obtained by an acid-catalysed cyclisation of the epoxide (R)-4. The enantiomeric excess of the product was 〉 95 %.

Notes: No abstract.

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A Regiospecific Photochemical Rearrangement of 2-Azabenzotricyclo[5.2.2.01,5]- to 2-Azabenzotricyclo[6.2.1.01,5]undecatrienone (1989)

Trifonov, Latchezar S. ; Dimitrov, Valentin S. ; Orahovats, Alexander S.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 502-506

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Notes: The 2-azatricyclo[5.2.2.01,5]undeca-4,8,10-trien-3-ones 1a and 1b gave on irradiation the 2-azatricyclo-[6.2.1.01,5]undeca-4,6,9-trien-3-ones 2a and 2b, respectively. The rearrangement was found to be solvent-, oxygen-, and wavelength-independant.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720313

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Syntheses of Bile Pigments. Part 16Part 15. Synthesis of a vinyl-substituted 2,3-Dihydrobilinedione: Possible role of this new class of bile pigments in phycobilin biosynthesis (1989)

Gossauer, Albert ; Nydegger, Fredy ; Benedikt, Eva ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 518-529

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Notes: The total synthesis of racemic cis-2,3,181, 182, -tetrahydroprotobiliverdin IXα dimethyl ester (19b), which is identical with the dimethyl ester of rac-4, is described (Scheme 2). Under virtually neutral conditions, in solution, this bile pigment isomerized within a few min to racemic Z-phycocyanobilin dimethyl ester (rac-5b). Likewise, acid-catalyzed allyl rearrangement of 3-vinyl-substituted cis- and trans-2,3-dihydrodipyrrin-1(10H)-ones 11c and 13c, respectively, yielded the corresponding ethylidene derivatives. In this case, however, the E-isomer was formed stereo selectively from both substrates. The above results prove that, if protobiliverdin IXα (2) is transformed enzymatically to its 2,3,181, 182-tetrahydro derivative, the latter would isomerize spontaneously to phycocyanobi-lin. The biosynthesis of bacteriochlorophyll a and b from a common precursor bearing a vinyl group at C(8)may be straightforwardly explained in the same way.

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Neue Sulfobutyl-haltige Bis(dimethinmerocyanin)-Farbstoffe mit isolierten Chromophoren im Molekül und deren Aggregationsverhalten in wässeriger Lösung (1989)

Kussler, Manfred ; Balli, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 638-647

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Notes: Novel Bis(dimethinemerocyanine) Dyes with Isolated Chromophores in the Molecule Containing the Sulfobutyl Group and their Aggregation Tendency in Aqueous SolutionThe bis(dimethinemerocyanine) dyes 7a-c with Chromophores separated by a polymethylene chain as ‘isolator’ are synthesized in good yield. Their aggregation tendency in organic solvents, organic solvents/H2O mixtures, and in H2O is investigated. In organic solvents, the dyes 7a-b show a splitted absorption band, due to interaction of the two Chromophores of the dye. In H2O, 7a exhibits an intense absorption band at 496 nm (∊ = 224 300 1·mol-1·cm-1) with a small width \documentclass{article}\pagestyle{empty}\begin{document}$ (\tilde v_{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}} = 1000\;{\rm cm}^{ - 1}) $\end{document} and shoulders at 552 and 580 nm. In presence of starch, this absorption band shifts to 617 nm, probably due to J-aggregation. The dye 7b shows the same spectral behaviour as 7a. In contrast, 7c exhibits an absorption band without splitting in organic solvents; the interaction of the Chromophores has disappeared. In H2O and in H2O containing starch, 7c shows a wide absorption band, due to interaction of the Chromophores of the dye.

Additional Material: 4 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720403

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Structure Determination of New Isomeric Naphtho[2,3-b]furan-4,9-diones from Tabebuia avellanedae by the selective-INEPT technique (1989)

Wagner, Hildebert ; Kreher, Bernhard ; Lotter, Hermann ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 659-667

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Notes: Beside the known naphthoquinones, dehydro-α-lapachone (17) and lapachol (20), four new naphtho[2,3-b]-furan-4,9-diones, i.e. the 2-acetyl-5-hydroxy. 2-acetyl-8-hydroxy. (-)-5-hydroxy-2-(1′-hydroxyethyl), and (±)-8-hydroxy-2-(1′-hydroxyethyl) derivatives 16, 15, 12, and 13, respectively, and the new compound benzo[b]furan-6-carboxaldehyde (8) have been isolated from a CHCl3 extract of the inner stem bark of Tabebuia avellanedae LORENTZ ex GRISEB., together with four known naphthofurandiones, a dihydroisocoumarin derivative, (-)-6-hydroxymellein, and five benzoic-acid and three benzaldehyde derivatives which have not been reported previously from this plant. Structure determination of the isomeric 5- and 8-hydroxynaphtho[2,3-b]furan-4,9-diones was carried out unambiguously by a combination of selective-INEPT experiments and X-ray crystallographic analysis.

Additional Material: 2 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720406

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Synthesis of (+)-(4S, 8R)hyphen;8hyphen;Epi- and (-)-(4R, 8S)-4-Epi-β-bisabolol (1989)

Fráter, Georg ; Müller, Urs

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 653-658

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The first total enantioselective synthesis of (+)-(4S, 8R)-8-epi-β-bisabolol(+)-1 and of (-)-(4R, 8S)-4-epi-β-bisabolol ((-))-1) is reported. The key step in the synthesis is the kinetic resolution of (±)-5 by means of the Sharpless epoxidation yielding (-)- and (+}-6, respectively. Reduction of the epoxides with LiAlH4 gave the diols (+)-and(-)-7 which were transformed into (+)- and (-)-8, respectively, via the corresponding mesylate. Reaction of these epoxides with the Grignard reagent derived from homoprenylbromide, assisted by Li2CuCl4, finished the synthesis of the target compounds 1 with high diastereo- and enantioselectivity.

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URL: http://dx.doi.org/10.1002/hlca.19890720405

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Notiz über mikrobiologische Umsetzungen mit Halobacterium halobium: Reduktion von 3-Oxobutansäure-ethylester und Hydrolyse von 3-Hydroxybutansäure-ethylester. Cooperative Effekte von Reduktase und Hydrolase (1989)

Ehrler, Jürg ; Seebach, Dieter

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 793-799

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Notes: Note on Biotransformations with Halobacterium halobium: Reduction of Ethyl 3-Oxobutanoate and Hydrolysis of Ethyl 3-Hydroxybutanoate. Cooperative Effects of Reductase and HydrolaseThe archaebacterium Halobacterium halobium, growing in saturated NaCl solution, is tested for its ability to achieve biotransformations. We found that this microorganism does accept only a small variety of compounds as substrates. Ethyl acetoacetate (1) is reduced to ethyl (S)-3-hydroxybutanoate (2) of optical purity of 40-76%, but in low chemical yields. The reduction is accompanied by hydrolysis of the hydroxy-ester to 3-hydroxybutanoic acid (3). Hydrolysis of rac-ester 2 by Halobacterium halobium gives (R)-2 of optical purity of up to 88%, depending upon reaction time, together with the almost racemic hydroxy-acid 3, both in low chemical yields. Hopes that the ‘extremist’ Halobacterium halobium would be able to effect unique conversions were not fulfilled.

Additional Material: 4 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720420

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2,2′-Bifurylidene-5,5′-diones, Coumarins, 3a, 7a-dihydro-1H-inden-1-ones, and 5H-furo[3,2-b]pyran-5-ones from propyne and carbon monoxideDedicated to Dr. G. Ohloff on the occasion of his 65th birthday (1989)

Rautenstrauch, Valentin ; Mégard, Patrick ; Gamper, Betty ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 811-824

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: The [Co2 (CO)8]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated. There are five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione (4), 3,5,8-trimethylcoumarin (8), 3a, 7a-dihydro-2,4,7,7a-tetramethyl-1H-inden-1-one (9), 2,6-dimethyl-5H-furo [3,2, -b]- pyran-5-one (11), and 2,7-dimethyl-5H-furo 3,2-b-pyran-5-one (12); of these, only one, 4. had previously been recognized. In parallel experiments were obtained 2,6-dipentyl-5 H-furo[3,2-b]pyran-5-one (13), 2,7-dipentyl-5H-furo[3,2-b]pyran-5-one (14), 3a, 7a-dihydro-2,4,7,7a-tetrapentyl-1H-inden-1-one (15). And 3a, 7a-dihydro-2,4,6,7a-tetrapentyl-1H-inden-1-one (16) from hept-1-yne, and two further types of products from two atypical 1-alkynes: 3,6,9-tri(tert-butyl)-1-oxaspiro[4.4]nona-3,6,8-trien-2-one (20) from (tert-butyl)acetylene and the exo-dimer 21 of 2,5-bis(trimethylsilyl)cyclopenta-2,4-dien-1-one (22) from (trimethylsilyl)acetylene. Compounds 11,12, and 20 were identified by X-ray analysis.

Additional Material: 1 Ill.

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URL: http://dx.doi.org/10.1002/hlca.19890720423

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Synthesis of 4-Alkoxy-1,3-oxazol-5(2H)-ones, Precursors of 1-alkoxy substituted nitrile ylides (1989)

Bozhkova, Nina ; Heimgartner, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 825-837

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: 4-Alkoxy-1,3-oxazol-5(2H)-ones of type 4 and 7 were synthesized by two different methods: oxidation of the 4-(phenylthio)-1,3-oxazol-5(2H)-one 2a with m-chloroperbenzoic acid in the presence of an alcohol gave the corresponding 4-alkoxy derivatives 4, presumably via nucleophilic substitution of an intermediate sulfoxide (Scheme 2). The second approach is the BF3-catalyzed condensation of imino-acetates of type 6 and ketones (Scheme 3). The yields of this more straightforward method were modest due to the competitive formation of 1,3,5-triazine tricarboxylate 8. At 155°, 1,3-oxazol-5(2H)-one 7b underwent decarboxylation leading to an alkoxy-substituted nitrile ylide which was trapped in a 1,3-dipolar cycloaddition by trifluoro-acetophenone to give the dihydro-oxazoles cis- and trans-9 (Scheme 4). In the absence of a dipolarophile, 1,5-dipolar cyclization of the intermediate nitrile ylide yielded isoindole derivatives 10 (Schemes 4 and 5).

Additional Material: 2 Ill.

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Mitteilungen (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 856-857

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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.19890720427

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Radikalische Cyclisierungen von Alkenyl-substituierten 4,5-Dihydro-1,3-thiazol-5-thiolenVorgetragen (H. H.) am ‘11th International Congress of Heterocyclic Chemistry’, Heidelberg, 16-21. August 1987. (1989)

Jenny, Christjohannes ; Wipf, Peter ; Heimgartner, Heinz

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 838-846

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Notes: Radical Cyclizations of Alkenyl-Substituted 4,5-Dihydro-1,3-thiazole-5-thiolsHeating of 5-alkenyl- or 5-alkinyl-4,5-dihydro-1,3-thiazole-5-thiols of type 5 in the presence of a radical initiator gave dithiaspirobicycles in fair-to-excellent yield (Scheme 3). Under analogous conditions, the 4,5-dihydro-4-vinyl-1,3-thiazole-5-thiol 5d underwent a cyclization to give the annellated dithiabicycle 7 (Scheme 4). In this reaction, a minor product 8 was formed by an unknown reaction mechanism. The structure of 8 was established by X-ray crystallography. The starting 1,3-thiazole-5-thiols 5 have been synthesized by carbophilic alkylation of me C=S group of 1,3-thiazole-5(4H)-thiones with Grignard-reagents or alkylcuprates. The thiazolethiones were obtained by the reaction of 3-amino-2H-azirines with thiobenzoic acid followed by sulfurization and cyclization. The 4-benzyl derivative 1b was thermally rearranged via 1,3-benzyl migration to yield the benzyl (1,3-thiazol-5-yl) sulfide 11 (Scheme 5).

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Masthead (1989)

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989)

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URL: http://dx.doi.org/10.1002/hlca.19890720501

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Stereoselektive Synthese von 3,5-disubstituierten Octahydroindolizinen (1989)

Vavrecka, Mojmir ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 847-855

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Notes: A Stereoselective Synthesis of 3,5-Disubstituted OctahydroindolizinesOn catalytic hydrogenation, methyl 6-nitro-9-oxodecanoate (1) underwent cyclization to 2 which, after hydrolysis, gave the bicyclic product 4. By another series of reactions, 2 was transformed to methyl 3-methyloctahydroindolizine-5-carboxylate (7), Conversions of 7a to its C(5)-epimer 7b and vice versa were accomplished and the configurations of 7a and 7b determined. Finally, 7b was reduced in three steps to 11 (overall yield from 1, 24%), which is an analog of several natural products.

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URL: http://dx.doi.org/10.1002/hlca.19890720426

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Photochemical Reactions 151st Communication150th Communication: [1]. Photo-oxygenation of (E)- and (Z)-7-Methyl-β-ionone (1989)

Nishio, Takehiko ; Mathies, Peter ; Job, Kurt ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 943-951

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Notes: Photo-oxygenation of (E)-7-methyl-β-ionone ((E)-1) and (E)-8-methyl-β-ionone ((E)-2) gave rise to the formation of the hydroperoxy-enones (E)-10 and (E)-15, respectively, which, in part, underwent intramolecular epoxidation to the hydroxy-epoxy-ketones 11 and 16, respectively, The product distribution of the photo-oxidation of (Z)-1 shows a marked influence of the skewed ground-state conformation of the dienone chromophore. Thus, singlet oxygen (1O2) was added to C(γ) of the dienone chromophore leading to the spirocyclic peroxy-hemiacetal 12 and to the endoperoxide 13. In addition, the tricyclic peroxide 14 was formed as a new type of product via primary addition of 1O2 to C(γ) of the dienone chromophore. The structure of 14 was established by X-ray crystal-structure analysis of the hemiacetal 22.

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Energy-Minimized Structures and Calculated and Experimental Isomer distributions in the hexaamine-cobalt(III) system [Co(L)2]3+ with the chiral facially-coordinating triamine (l = butane-1,2,4-triamine) (1989)

Comba, Peter ; Maeder, Marcel ; Zipper, Luc

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1029-1037

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Notes: Butane- 1,2,4-triamine (trab) is the smallest tridentate aliphatic unsubstituted chiral triamine. With optically pure trab, there are three, with racemic trab five isomers of [Co(trab)2]3+, One of the five isomers is centrosymmetrical, the others are chiral. For one of the isomers, there are four possible conformations (all combinations of chair and skew boat conformations for the chelate six ring of each ligand), for the others there exist only three independent conformers. All sixteen independent structures have been calculated by strain-energy minimization. The calculated isomer distribution, based on total strain energies corrected with statistical entropy contributions (21%:16%:16%:4%:43%, and 40%:30%:30%, for racemic and optically pure trab, respectively) are in excellent agreement with the experimental data based on HPLC and 13C-NMR analyses of equilibrium solutions of the hexaamine-Co(III) compounds prepared by oxygenation of aqueous solutions in presence of activated charcoal. The results are also briefly discussed in relation to possible stereoselectivity upon complexation of optically pure trab and a racemic chiral ligand to a transition-metal center.

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Enantioselective Synthesis: Steric and electronic effects of the substrates upon stereoselectivity in the gold(I)-catalyzed aldol reaction with chiral ferrocenylamine ligands, preliminary communication (1989)

Togni, Antonio ; Pastor, Stephen D.

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1038-1042

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Notes: Enantioselectivity in the gold(I)-catalyzed aldol reaction with chiral ferrocenylamine ligands is strongly dependent upon both the steric and electronic effects of the substrates. In the reaction of pyridine-2-, 3-, and 4-carbaldehydes with ethyl 2-isocyanoacetate, surprisingly and significantly different enantioselectivities were observed in the formation of the cis- and trans-dihydro-oxazoles that must be due to electronic rather than steric effects. The first example of double stereodifferentiation in the gold(l)-catalyzed aldol reaction is reported.

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URL: http://dx.doi.org/10.1002/hlca.19890720521

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The Carbonyl Group as Homoconjugated Electron-Releasing Substituent. Regioselective electrophilic additions at bicyclo[2.2.1]hept-5-en-2-one, bicyclo[2.2.2]oct-5-en-2-one, and derivativesPresented at the autumn meeting of the Swiss Chemical Society in Berne, October 17, 1980; for a preliminary communication, see [1a]. (1989)

Carrupt, Pierre-Alain ; Vogel, Pierre

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1008-1028

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: In CHCl3, CH3CN, or AcOH, benzeneselenenyl chloride (PhSeCl), bromide (PhSeBr), and acetate (PhSeOAc), 2-nitrobenzenesulfenyl chloride (NO2C6H4SCl), and 2,4-dinitrobenzenesulfenyl chloride ((NO2)2C6H3SCl) added to bicyclo[2.2.1]hept-5-en-2-one (5) in an. anti fashion with complete stereo- and regioselectivity, giving adducts 20-24 in which the chloride, bromide, or acetoxy substituent (X) occupies the endo position at C(6) and the Se- or S-substituent (E) the exo position at C(5), The addition 5+ (NO2)2C6H3SCl→24 was accompanied by the formation of (1RS, 2RS)-2-(2,4-dinitrophenylthio)cyclopent-3-ene-l-acetic acid (25). The latter was the major product in AcOH containing LiClO4. The additions of PhSeCl and PhSeBr to bicyclo[2.2.2]oct-5-en-2-one (6) were less stereoselective (proportion of exo vs. endo mode of electrophilic attack was ca. 3:1) but highly regioselective gazing adducts 27/28 and 29/30, respectively, the regioselectivity being the same as that of the electrophilic additions of 5. The reaction of PhSeCl with a 4:1 mixture of 2-exo-chloro- and 2-endo-chlorobicyclo[2.2.1]hept-5-ene-2-carbonitriles (12) was slower than addition 5+ PhSeCl; it gave adducts 31/32 (4:1) in which the PhSe moiety occupies the exo position at C(6) and the Cl atom the endo position at C(5). The addition of PhSeCl to 2-chlorobicyclo[2.2.1]oct-5-ene-2-carbonitriles (13) was very slow and gave adducts with the same regioselectivity as 12 + PhSeCl, but opposite with that of reactions of the corresponding enones 5 and 6. PhSeX (X = Cl, Br, OAc) added to 2-cyanobicyclo[2.2.1]hept-5-en-2-yl acetates (14) with the same regioselectivity as 12 + PhSeCl. The additions of PhSeCl, PhSeBr, NO2C6H4SCl, and (NO2)2C6H3SCl to 2-(bicyclo[2.2.1]hept-5-en-2-ylidene)propanedinitrile (49) were not regioselective, showing that a dicyanomethylidene function is not like a carbonyl function when homoconjugated with a π system. The results are in agreement with predictions based on MO calculations suggesting that a carbonyl group homoconjugated with an electron-deficient centre can behave as an electron-donating, remote substituent because of favourable n(CO)↔σC(1), C(2)↔p(C(6) hyperconjugative interaction.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720519

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Synthesis and NMD A Antagonistic Properties of the Enantiomers of 4-(3-phosphonopropyl)piperazine-2-carboxylic acid (CPP) and of the unsaturated analogue (E)-4-(3-phosphonoprop-2-enyl)piperazine-2-carboxylic acid (CPP-ene) (1989)

Aebischer, Bernard ; Frey, Peter ; Haerter, Hans-Peter ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1043-1051

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The (R)- and (s)-enantiomers of 4-(3-phosphonopropyl)piperazine-2-carboxylic acid (D- and L-CPP, resp.; 15 and 16, resp.), and of its unsaturated analogue (E)-4-(3-phosphonoprop-2-enyl)piperazine-2-carboxylic acid (D- and L-CPP-ene, resp.; 13 and 14, resp.) were prepared. The absolute configuration of the enantiomers was determined by a chemical correlation of the menthyl ester 7 with D-asparagine. The affinity of these derivatives for the NMDA receptor was determined by displacement of [3H]CPP in rat cerebral cortical membranes. In two functional tests (the frog hemisected spinal cord preparation and the sodium efflux test from rat brain slices), D-CPP-ene appears to be the most potent, enantiomerically pure, competitive NMDA antagonist known to date.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720522

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Chloride Binding by Polyammonium Receptor Molecules: 35Cl-NMR Studies (1989)

Hosseini, Mir Wais ; Kintzinger, Jean-Pierre ; Lehn, Jean-Marie ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1078-1083

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Binding of chloride anion by protonated polyamines was investigated by 35Cl—NMR spectroscopy. The presence of protonated macro(poly)cyclic polyamines caused downfield shifts and significant line broadening of the 53Cl—NMR signals. 35Cl—NMR spectroscopy was used for complex-formation stoichiometry determination and revealed the formation of a binuclear chloride complex with the fully protonated ditopic hexaazamacrocyclic receptor 6. 35Cl—NMR spectroscopy was also applied in competition experiments between Cl— and SO42- and demonstrated that the fully protonated macrocyclic hexaamine 4 forms a strong complex with SO4-2 with 1:1 stoichiometry.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720526

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New Spirostaphyiotrichins from the Mutant Strain P 84 of Staphylotrichum coccosporum (1989)

Sandmeier, Peter ; Tamm, Christoph

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1107-1120

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: From a mutant strain of S. coccosporum, the new spirostaphylotrichins E (2), F(3), G (4 or 5), H (5 or 4), I (6), K (7), L (8), M (9), and S (10) have been isolated. Their structures have been elucidated by spectroscopic methods (UV, IR, 1H—NMR, 13C—NMR, and MS), chemical transformations, and X-ray analysis (3 and 7).

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/hlca.19890720529

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2′, 3′-Dideoxy-3′-fluorotubercidin and Related Dideoxyribonucleosides:. Synthesis via a 2′-deoxy-3′-oxoribofuranoside intermediate and conformation studies (1989)

Rosemeyer, Helmut ; Seela, Frank

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 72 (1989), S. 1084-1094

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: An efficient synthesis of the unknown 2′-deoxy-D-threo-tubercidin (1b) and 2′, 3′-dideoxy-3′-fluorotubercidin (2) as well as of the related nucleosides 9a, b and 10b is described. Reaction of 4-chloro-7-(2-deoxy-β-D-erythro-pentofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine (5) with (tert-butyl)diphenylsilyl chloride yielded 6 which gave the 3′-keto nucleoside 7 upon oxidation at C(3′). Stereoselective NaBH4 reduction (→8) followed by deprotection with Bu4NF(→9a)and nucleophilic displacement at C(6) afforded 1b as well as 7-deaza-2′-deoxy-D-threo-inosine (9b). Mesylation of 4-chloro-7-{2-deoxy-5-O-[(tert-butyl)diphenylsilyl]-β-D-threo-pentofuranosyl}-7H-pyrrolo[2,3-d]-pyrimidine (8), treatment with Bu4NF (→12a) and 4-halogene displacement gave 2′, 3′-didehydro-2′, 3′-dideoxy-tubercidin (3) as well as 2′, 3′-didehydro-2′, 3′-dideoxy-7-deazainosne (12c). On the other hand, 2′, 3′-dideoxy-3′-fluorotubercidin (2) resulted from 8 by treatment with diethylamino sulfurtrifluoride (→10a), subsequent 5′-de-protection with Bu4NF (→10b), and Cl/NH2 displacement. 1H-NOE difference spectroscopy in combination with force-field calculations on the sugar-modified tubercidin derivatives 1b, 2, and 3 revealed a transition of the sugar puckering from the 3′T2′ conformation for 1b via a planar furanose ring for 3 to the usual 2′T3′ conformation for 2.

Additional Material: 5 Tab.

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URL: http://dx.doi.org/10.1002/hlca.19890720527

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