摘要:

From cultures of the Avilamycin (Avilamycin A) producing organism,Streptomyces viridochromogenes, strain ETH 23575, a second antibiotic, Avilamycin C, C61H90Cl2O32could be isolated in crystalline form. Both Avilamycins belong to the group of the Orthosomycins. By IR.,1H‐ and13C‐NMR. spectroscopy and by transformation to a common derivative it could be proven that Avilamycin A is a methyl ketone, Avilamycin C the corresponding methyl carbi

ISSN:0018-019X    

DOI:10.1002/hlca.19790620102

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Hydrolysis and methanolysis of Avilamycin C yielded a series of mono‐ and oligosaccharide‐like products, which were, with one exception, identical with degradation products of flambamycin. Instead of evalose (6‐deoxy‐3‐methyl‐D‐mannose), a building stone of Flambamycin and Everninomicin B, evermicose (2, 6‐dideoxy‐3‐methyl‐D‐mannose) was identified as a constituent of the Avilamycins. This sugar was known as a degradation product of the Everninomicins C and D. From the degradation results a structure of Avilamycin A was postulated which differs from that of Flambamycin only by the lack of a hydroxyl group in position 2 of the evalose residue. This hypothesis was confirmed by a caref

ISSN:0018-019X    

DOI:10.1002/hlca.19790620103

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractStudy of heteroaromatic radicals. Part XV.Partie XIV:cf. [1].Aprotic decomposition of 6‐amino‐2‐ethylbenzothiazole in aromatic and heteroaromatic substrates: preparation of 6‐mesityl‐ and 6‐furyl‐2‐ethylbenzothiazoles and of the corresponding quaternary salts and spyropyransIn the presence of excess isopentyl nitrite in aprotic solvent, the 6‐amino‐2‐ethyl‐benzothiazole leads to 6‐aryl‐ and 6‐heteroaryl‐2‐ethylbenzothiazoles1to14inca.20–50% yield (Scheme 1, Table 1). The 2‐ethyl‐6‐benzothiazolyl radicals generated during these reactions exhibit a weak electrophilic character(Table 2).Preparatively this method has been applied to the synthesis of 6‐mesityl‐ and 6‐furyl‐2‐ethylbenzothiazoles6and7, which were used to prepare the corresponding quate

ISSN:0018-019X    

DOI:10.1002/hlca.19790620104

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe13C‐NMR. spectrum of dihydrogranaticin methyl ester has been completely analyzed. Feeding experiments of CH313COONa to a culture ofStreptomyces olivaceushave shown that only a sixteen carbon moiety of the antibiotic granaticin is of polyketide origin, thus confirming the hypothesis of a mixed biogenesis for this natural substanc

ISSN:0018-019X    

DOI:10.1002/hlca.19790620105

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe synthesis of bicyclo [4.4.1] undec‐1 (11)‐ene (5) by intramolecularWittigreaction is described. TheBredtolefin could not be isolated, but dimerized rapidly to a novel compound15containing a cyclopropane ring. The olefin5was trappedin situby 2,5‐diphenylbenzo [c]

ISSN:0018-019X    

DOI:10.1002/hlca.19790620106

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe isolation and synthesis of (cis‐6‐methyltetrahydropyran‐2‐yl)acetic acid (1a), a novel compound from civet (Viverra civetta), are r

ISSN:0018-019X    

DOI:10.1002/hlca.19790620107

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Cob (I)alamin as Catalyst 3. Communication [1]. Examination of an Enantioselective Reduction Using α,β‐Unsaturated Estersα,β‐Unsaturated esters can be reduced to the corresponding saturated esters using catalytic amounts of cob (I)alamin in the presence of an excess of zinc. An enantioselective reduction has been observed starting from ethyl (Z)‐3‐methyl‐5‐phenyl

ISSN:0018-019X    

DOI:10.1002/hlca.19790620108

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractPd (CO) (PPh3)3could be isolated from the reaction mixture arising from cyclohexene hydrocarboxylation by PdCl2(PPh3)2as the catalyst precursor; furthermore, it has also been prepared through direct reaction of Pd (PPh3)4with CO in benzene. For this complex,31P‐ and13C‐NMR. spectra suggest a rapid dissociation of PPh3at room temperature and a tetrahedral structure at – 70° in so

ISSN:0018-019X    

DOI:10.1002/hlca.19790620109

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe aromatic1H‐ and13C‐NMR. spectra of some metal complexes of o, o′‐dihydroxyazobenzenes are shown to be useful in distinguishing the two possible isomers (acolar and discolar) stemming from the non equivalence of the two ligating azo nitrogen atoms. The ortho aromatic carbon atoms, C(6) and C(12) experience relatively large upfield shifts between 12.8 and 15.7 ppm when the adjacent nitrogen atom is coordinated. The protons attached to these carbon atoms are shifted downfield. The valuesnJ(15N,13C) for the ligand 2,2′‐dihydroxy‐3‐methyl‐4′‐chloro‐5‐(t‐butyl)

ISSN:0018-019X    

DOI:10.1002/hlca.19790620110

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Megastigma‐5,8‐dien‐4‐one, an aroma constituent of the yellow passion fruit andVirginiatobaccoPreparative gas chromatography allowed isolation of megastigma‐5, 8 (E)‐dien‐4‐one (3) from small subfractions of both yellow passion fruit andVirginiatobacco condensates. Along with3, the Z‐isomer4occurs in the aroma of the yellow passion fruit. Both these novel flavor compounds were synthesized by a two‐step, non‐biomimetic route starting from 2, 6, 6‐trimethylcyclohex‐2‐en‐1‐one. TheE‐isomer3was also formed by acid‐catalyzed dehydration/rearrangements of ionol‐ and damascol monoepoxides5, 6, 7, 8and hydroxy‐ionols and ‐damascol9, 10and11. Such a biomimetic conversion indirectly supports the assumption that3and4might originate from the oxidative degradation of carotenoid prec

ISSN:0018-019X    

DOI:10.1002/hlca.19790620111

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY