摘要:

AbstractThe title compound, an analogue of [Leu5]‐enkephalin withL‐o‐carboranylalanine replacingL‐phenylalanine in position 4, was prepared by fragment condensation. The analogue has a 3‐fold higher affinity for rat brain opiate receptors in the [3H]naloxone competition assay than natural [Leu5]‐enkephalin. Like [Leu5]‐enkephalin andNa‐acetyl‐[Leu5]‐enkephalin, theN‐terminal tripeptide fragment, H · Tyr‐Gly‐Gly · OH, had no melanotropic activity in theRana pipiensfrog skin assay.A convenient, direct synthesis of methylt‐butoxycarbonyl‐L‐propargylglycinate is described, and the13C‐NMR. spectra ofL‐o‐carboranylalanine recorded. The procedure was extended to the preparation of BOC · Car‐Leu · OMe from BOC · Pra‐Leu · OMe. A number o

ISSN:0018-019X    

DOI:10.1002/hlca.19790620502

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Lucibufagins. Part IIICommunication no. 63 de la série ‘Defense Mechanisms of Arthropods’. Pour no. 62, voir [1]..11‐Oxo‐and 12‐oxo‐bufalins, defensive steroids from the firefliesPhotinus ignitusandP. marginellus (Coleoptera: Lampyridae)Four lucibufagins (4,8,9and10), defensive bufadienolides from the firefliesPhotinus ignitusandP. marginellus (Coleoptera: Lampyrida), have been isolated and are characterized by spectro

ISSN:0018-019X    

DOI:10.1002/hlca.19790620503

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

CyanohalogenomethylidenetriphenylphosphoranesIodo‐, bromo and chlorocyanomethylidenetriphenylphosphoranes are described as well as a procedure for thein situgeneration of cyanofluoromethylidenetriphenylphosphorane. These ylides are reactive towards aldehydosugar

ISSN:0018-019X    

DOI:10.1002/hlca.19790620504

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe conversion of primary, secondary and vinylic halides to the two C‐atoms homologated phenylselenomethyl ketones8is described. The method involves addition of the readily available phenylselenoacetaldehyde5to theGrignardreagents9and oxidation of the resulting β‐hydroxy‐selenides10(Sch

ISSN:0018-019X    

DOI:10.1002/hlca.19790620505

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Preparation of Stilbenyl Derivatives of 1,2,4‐OxadiazolesSchiffsbases derived from 3‐ and 5‐(p‐formylphenyl)‐phenyl‐1,2,4‐oxadiazoles and chloroanilines are reacted with variousp‐tolyl substituted aromatic heterocycles in the presence of dimethylformamide and potassium hydroxide to yield the corresponding heterocyclic substituted stilbenes (‘Anil synthesis’). The reactivity of 5‐[4‐(chlorophenylimino‐methyl)phenyl]‐3‐phenyl‐1,2,4‐oxadiazoles is very low an

ISSN:0018-019X    

DOI:10.1002/hlca.19790620506

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Addition Reaction of 3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine with Phenylisocyanate and Diphenylketene3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine (1a) reacts with carbon disulfide and isothiocyanates with splitting of the azirine N(1), C(3)‐double bond to give dipolar, fivemembered heterocyclic 1:1 adducts. In some cases, these products can undergo secondary reactions to yield 1:2 and 1:3 adducts. In this paper it is shown that the reaction of1awith phenylisocyanate also takes place by cleavage of the N(1), C(3)‐bond, whereas with diphenylketene N(1), C(2)‐splitting is observed.The reaction of1aand phenylisocyanate in hexane at room temperature yields the 1:3 adduct2in addition to the trimeric isocyanate3(Scheme 1). A mechanism for the formation of2is given inScheme 5. Hydrolysis experiments with the 1:3 adduct2, yielding the hydantoins4–6and the ureas7and8(Schemes 3and5), show that the formation of this adductviathe intermediatesd,eandfis a reversible reaction.The aminoazirines1aand1bundergo an addition reaction with diphenylketene to give the 3‐oxazolines14(Scheme 8), the structure of which has been established by spectral data and oxidative degradation of14ato the 3‐oxazoli

ISSN:0018-019X    

DOI:10.1002/hlca.19790620507

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

(Perhalomethylthio)heterocycles. XIX. Mitt.: s. [1]..Acid‐catalyzed substitutions on (perchlorofluoromethylthio)pyrroles and their agro‐biological activitiesIn the presence of C4F9SO3H the (perhalomethylthio)pyrroles1a–creact with Cl3−nFnCSCl (n = 1–3) to give mixtures of the 2,5‐ and 2,4‐disubstituted pyrroles2a–fand3a–h.2aand3areact with CF3SCl (catalyst CF3SO3H) yielding 2,3,5‐tris (trifloromethylthio)pyrrole (4a), which under similar conditions reacts further to give 2,3,4,5‐tetrakis (trifluoromethylthio)pyrrole (5). As a by‐product during the conversion of3ato4a2,3,4‐tris (trifluoromethylthio)pyrrole (4b) is formed. The pyrroles2a,4aand5form the mercury salts6a–c; compound5yields also a silver salt7. The1H‐ and19F‐NMR. spectra are discussed and the agro‐biological propert

ISSN:0018-019X    

DOI:10.1002/hlca.19790620508

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

A new way to vinylic ethers from acetalsAcetals react at low temperatures in presence of aLewisacid (aluminium chloride or magnesium bromide) with tertiary amine to give in good yields the vinylic ethers corresponding to the elimination of one molecule of alcohol.

ISSN:0018-019X    

DOI:10.1002/hlca.19790620509

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

1H‐NMR. Spectroscopic Analysis of Prochiral Allenic Esters Using Optically Active Europium Shift ReagentsThe prochiral allenic methyl esters1–4(cf. Scheme)show in the presence of 1 mol‐equiv. tris[3‐(heptafluorobutyryl)‐(+)‐camphorato]europium (III) (Eu (hfc)3) in 1,1,2‐trichloro‐1,2,2‐trifluoroethane (TCFE) induced unlike1H‐NMR. shift differences (ΔΔδ) for the enantiotopic protons and methyl groups on C(4), respectively (cf. Fig. 2and3). This effect allows to determine directly the2JH,Hcoupling constants of the geminal protons on C(4) of the allenic esters1(15.5 Hz) and2

ISSN:0018-019X    

DOI:10.1002/hlca.19790620510

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Heterocyclic anellated derivatives of strychnine: Imidazo‐, oxazolo‐ and (1,3‐dioxolo)strychnineThe synthesis of imidazo‐, oxazolo‐ and dioxolo‐strychnine derivatives, anellated at the 2,3‐position of the aromatic nucleus is described. The spectroscopic properties of these compounds and of some intermedia

ISSN:0018-019X    

DOI:10.1002/hlca.19790620511

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY