ISSN:0018-019X    

DOI:10.1002/hlca.19830660502

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractA series of compounds possessing a ‘Steroid‐type’ scent and related to 4‐(4′‐t‐butylcyclohexyl)‐4‐methyl‐2‐pentanones (1and2) has been synthesized. The odor of these compounds has been found to be dependent on their conformation; only when the molecule can assume a steroid‐like shape there is an interaction with

ISSN:0018-019X    

DOI:10.1002/hlca.19830660503

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractL‐Phenylalanine has been treated with chlorosulfonic acid and the product was either hydrolyzed, ammonolyzed or reduced. The resulting sulfonic‐acid and aminosulfonyl derivatives have been employed for peptide synthesis with Boc‐protection of the Nα‐position only. The reduction productL‐(4′‐SH)Phe has been protected by formation of asymmetric disulfides or with various thiol protecting groups (benzyl‐, methyl‐ and acetamidomethyl groups, the latter being the most suitable for peptide synthesis).With these protected amino acids several analogues of angiotensin II have been synthesized by the solid‐phase method. These analogues have been used for structure‐activity relationship studies on thr

ISSN:0018-019X    

DOI:10.1002/hlca.19830660504

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Addition Reactions of 2‐Amino‐1‐azetines with Cyclopropenones; Formation of Azepine Derivatives by Ring Expansion ReactionsThe reaction of 2‐amino‐1‐azetines of type6with 2,3‐diphenylcyclopropenone (1a) in acetonitrile leads to azetol[1,2‐α]pyrroles (cf.7and9,Schemes 3and4) in good yield. It is remarkable that in the reaction of6awith1aonlyendo‐7is formed. With silicagel in etherendo‐7isomerizes to the thermodynamically more stableexo‐7(Schemes 3and6). The crystal structure of the latter compound has been established by X‐ray crystallography. The reaction of6aand 2‐isopropyl‐3‐phenyl‐cyclopropenone (1b) yields only one product, which isomerizes with silicagel in ether toexo‐10(Scheme 4). The structure ofexo‐10has been determined by NMR‐spectroscopy. It seems reasonable that this structure results from a nucleophilic attack of the four‐membered amidi

ISSN:0018-019X    

DOI:10.1002/hlca.19830660505

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Abstract1,2‐Didehydrocrotalanine (2) is the first synthetic macrocyclic pyrrolizidine alkaloid analogue to be studied by X‐ray crystallography. The crystal structure was solved by multisolution direct methods and refined by full‐matrix least‐squares toR= 0.036 for 693 reflections. The alkaloid analogue has an 11‐membered macrocycle containing two ester groups with their carbonyl groups nearly ant

ISSN:0018-019X    

DOI:10.1002/hlca.19830660506

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractFourteen sesquiterpene ketonesD–Qpertaining to the valencane (D–J) and eudesmane (K–Q) groups have been identified for the first time in grapefruit juice flavor. These novel grapefruit constituents, which include the six new compoundsI,J,L,M,NandO, were identified by direct comparison with synthetic samples. Organoleptically, their total contribution to grapefruit flavor is not negligible. In particular, (+)‐8,9‐didehydronootkatone (E) has a powerful flavor with good grapefruit juice

ISSN:0018-019X    

DOI:10.1002/hlca.19830660507

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

The cyclopentenecarbaldehyde1a, acetals2a,2band the cyclopentenone2chave been transformed through regio and stereocontrolled reactions into a variety of enantiomerically pure substituted cyclopentanes. Using appropriately selectedWittigreagents, aldehyde1afurnished the condensation products3,4,5.Michaeladdition of diethyl malonate on the α,β‐unsaturated aldehyde1aunder phasetransfer conditions led efficiently to7. Reduction of the cyclopentenone2cgave21in high yield. The cyclopentenes2a,2band23, submitted to hydroboration‐oxidation furnished the cyclopentanols10,13and24, respectively, in 30, 70 and 50% yields, reflecting the substitution pattern of the starting alkenes. The salient feature of these reactions is the stereospecificity due to the chiral centre of the molecules1a,2a,2band2c, leading to compounds with two, three and four asymmetric centres. The straightforward synthesis of 11α‐hydroxy‐13‐oxaprostanoic acid20is described and an approach towards the preparation of 9α, 11α‐dihydroxy‐13‐oxaprostanoic acid34is also presented. The structure of these products has been determined by1H‐ a

ISSN:0018-019X    

DOI:10.1002/hlca.19830660508

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractThe radical anions of 5,6‐didehydrobenzocyclooctene (3), 5,6,9,10‐tetradehydrobenzocyclooctene (4) and 1,4,7,10‐tetramethyl‐5,6‐didehydrodibenzo[a,e]‐cyclooctene (6) were preparedin situfrom dibromo‐precursors and have been characterized by ESR and ENDOR

ISSN:0018-019X    

DOI:10.1002/hlca.19830660509

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

3,3‐Dialkyltriazenecarboxylic Derivatives by Oxidative Hydro‐Acyl‐Elimination from 3,3‐Dialkyltriazane‐1,2‐dicarboxylic DerivativesThe preparation and some properties of esters and amides of 3,3‐dialkyltriazenecarboxylic acids (6) are described. These novel triazenes6were obtained by treatment of diesters, diamides and ester‐amides of 3,3‐dialkyltriazane‐1,2‐dicarboxylic acids (3) with lead tetraacetate, when an elimination of the COOR‐ or the CONHR‐group at N(2) together with the H‐atom at N(1) took place. The precursor triazanes3were readily available from the addition of secondary amines2to diesters, diamides or ester‐amides of diazenedicarboxylic acid (1). The spectral properties of the triazanes6, including the15N‐NMR signals of one example, are compared with those of the triazanes3. They express the structural features due to conjugation in 3,3‐dialkyltriazenecarboxylic derivatives, including the resistance to ro

ISSN:0018-019X    

DOI:10.1002/hlca.19830660510

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

Attempted Synthesis of Push‐Pull DiacetylenesTwo alternative synthesis of push‐pull diacetylenes of type1(5‐amino‐2,4‐alkadiynals) are investigated. A bromination‐dehydrobromination sequence starting with 5‐dimethylamino‐2,4‐pentadienal (2) as well as the application of the well‐knownCadiot‐Chodkiewiczcoupling reaction give new intermediates3–5, and7and8, respectively, but fail to giv

ISSN:0018-019X    

DOI:10.1002/hlca.19830660511

出版商:WILEY‐VCH Verlag GmbH    

年代:1983

数据来源: WILEY