摘要:

AbstractStarting from the γ‐lactonecis‐1, two new syntheses of γ‐damascone ((E)‐4) are described. In both syntheses, the key step involves the β‐cleavage of a bis(homoallylic) potassium alkoxide,viz.the transformation of3ato20and (E/Z)‐4, and the conversion of21ato

ISSN:0018-019X    

DOI:10.1002/hlca.19880710702

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractO‐Methylation of optically active 3′,4′‐dideoxynorlaudanosoline‐l‐carboxylic acids1withO‐methyltransferasein vitroafforded almost exclusively the 7‐O‐methylated acids3. A similar result was obtained with the yellow quinonemethide4Aobtained from1at neutral or slightly alkaline pH by oxidative decarboxylation and affording the 3,4‐dihydroisoquinoline15on methylation with catecholO‐methyltransferase (COMT). The structure of quinonemethide4Awas determined on the basis of spectral data, by its conversion into isoquinolines of established structure, and by synthesis. Quinonemethide4Awas found to be a weak inhibitor of monoamine oxidase A (MAO A) but not a substrate. Nonenzymatic oxidative decarboxylation of dopamine‐derived tetrahydroisoquinoline‐l‐carboxylic acids to quinonemethides may be a major factor in biochemical experimentation and should be considered in

ISSN:0018-019X    

DOI:10.1002/hlca.19880710703

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractUV Irradiation of 3‐oxocyclopent‐1‐enyl acetate (17) and acetylene in MeCN at 0° gives, besides the product of normal enone‐alkyne [2 + 2] cycloaddition (cis‐4‐oxobicyclo[3.2.0] hept‐6‐en‐1‐yl acetate,18) and its product of oxa‐di‐π‐methane rearrangement (5‐oxotricyclo[4.1.0.02,7]hept‐2‐yl acetate,19), unexpected products of further addition of a molar equivalent of acetylene. These are indanone ( = 2,3‐dihydro‐1H‐inden‐1‐one,16), in 21% yield,cis‐1‐cisoid‐1,2‐cis‐2‐ (20) andcis‐1‐transoid‐1,2‐cis‐2‐7‐oxotricyclo[4.3.0.02,5]non‐3‐en‐1‐yl acetate (21), 4‐oxo‐7‐‘exo’‐vinyltricyclo[3.2.0.02,6]hept‐2‐yl acetate (22),cis‐4‐oxo‐6‐‘endo’‐ (23) andcis‐4‐oxo‐6‐‘exo’‐vinylbicyclo[3.2.0]hept‐1‐yl acetate (24), andcis‐4‐oxo‐7‐‘exo’‐vinylbicyclo[3.2.0]hept‐1‐yl acetate (25). At least in part, indanone must be formedviaintermediates20and21. In fact, on heating a 9:1 mixture20/21, indanone is

ISSN:0018-019X    

DOI:10.1002/hlca.19880710704

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractGroup‐IV‐A phthalocyanines with four crown ether substituents have been prepared from 4′,5′‐dicyanobenzo(15‐crown‐5), 4′,5′‐diiminoisoindolino(15‐crown‐5), or metal‐free phthalocyanine and the corresponding metal salts. The axial ligands of dichloro[tetra(15‐crown‐5)phthalocyaninato]silicon or ‐tin have been converted into dihydroxy derivatives by hydrolysis in aqueous Et3N. The catalytic effect of H2O‐free CaC12in quinoline is used for the polycondensation of dihydroxysilicon‐phthalocyanine to cofacially arrayed polymers. The thermal stability of group‐IV‐A‐metal phthalocyanines is confirmed by the higher initial decomposition points (290–440°) compared to those of the co

ISSN:0018-019X    

DOI:10.1002/hlca.19880710705

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe synthesis and antifungal activity of a novel series of 1‐[(3,5‐bisaryl‐2‐methylisoxazolidin‐3‐yl)methyl]‐1H‐1,2,4‐triazoles6and7(i.e.8–19) are discussed. The preparation of8–19was straightforward and highlighted by a regiospecific 1,3‐dipolar cycloaddition of α‐substituted (E)‐ketonitrones4with appropriate atyrene derivatives5that led to acis/trans‐diastereoisomeric mixture of the corresponding triazoles (Scheme). The title compounds were evaluated forin vitroantifungal activity in solid agar cultures against a broad array of yeast and systemic mycoses and dermatophytes. Thein vivoactivity was determined in an immune‐compromised mouse model of systemic candidiasis. While thein vitroactivity was evident throughout the series, it was moderate in potency. However, some of the triazole derivatives demonstrated a potentin vivoactivity comparable to that of the standard drug ketoconazole. Analogue12(PR 988‐399) emerged as the best overall compound demonstrating potent antifungal activi

ISSN:0018-019X    

DOI:10.1002/hlca.19880710706

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractBase‐induced elimination of dichlorocarbene adducts2to 9‐alkoxyphen threnes1leads to furans6, presumablyviacyclopropenes3which undergo rearrangement to vinylcarbenes4and CH insertion. By the same sequence, the 9‐substituted alkylphenanthrene adduct10and14afford cyclopentadienes11and15. Carbene adducts of simple enol ethers, however, react differently and give preferentially 2‐chloroalk

ISSN:0018-019X    

DOI:10.1002/hlca.19880710707

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

Structure and Partial Synthesis of Dimeric Coleon FColeon F (1a), on standing in solution, slowly dimerizes to the labile C(7)‐epimeric spiro‐dihydrofuranes2a/2bwhose structures were elucidated by spectroscopic methods. Oxydative addition of1ato another molecule of1ain the presence ofFétizon's reagent rapidly yields2a/2b, thus confirming their structures as (4bS,9RS,10′aS)4,4a,10′,10′a‐tetrahydro‐1′,6‐dihydroxy‐1,2,4a,7′,8′,10′a‐hexamethyl‐3′,7‐bis(2‐propenyl)‐spiro[3H,9H‐phenanthren‐9,5′‐5

ISSN:0018-019X    

DOI:10.1002/hlca.19880710708

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe dimethyl acetals4of(E)‐2,4‐pentadienal and of (E,E)‐ and (E,Z)‐2,4‐hexadienals undergo regio‐ and stereospecific cycloaddition reactions within‐situ‐generated acylnitroso dienophiles5aand5b, leading thereby to the corresponding dihydrooxazines7a–dand8c–d.cis‐Glycolization of these latter adducts stereospecifically gave the dihydro derivatives9a–dand10dwhich, after sequential hydrogenolysis, deacetalization, and instant cyclization, led to the aminodeoxyribose derivatives17a, 17f, and18, and to the amino‐dideoxyallose compounds17cand17h. These piperidino‐deoxysugar derivatives exhibit a strong anomeric effect,i.e.OHC(1) is always axial, which is explained in terms of a nN(π)‐σ*(COH) orbital compression, as compared to the less pronounced one in

ISSN:0018-019X    

DOI:10.1002/hlca.19880710709

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractO‐Labelled carbon monoxide was prepared on the gram scale from enriched water and acetals of norborn‐2‐en‐7‐one(= bicyclo[2.2.1]hept‐2‐en‐7‐one) in almost quantitative yields and without

ISSN:0018-019X    

DOI:10.1002/hlca.19880710710

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractIt is shown that the acidity dependence of the rate of nitrosation of aromatic amines and of hydroxylamine in strongly acidic aqueous solutions does not necessarily involve the rearrangement of a charge transfer complex (consisting of the NO+ion and the substrate with an NH 3+group) in concert with a proton loss at the NH 3+group. More likely, proton loss of the charge complex preceeds the π → N rearrangement of the

ISSN:0018-019X    

DOI:10.1002/hlca.19880710711

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY