摘要:

AbstractIn the presence of dilute alkali at room temperature aldosterone undergoes rearrangement to form 11β,18:18,21‐diepoxy‐20,21‐dihydroxy‐4‐pregnen‐3‐one (V). X‐Ray crystallographic analysis demonstrates that isomers of both 18R, 20S, 21S and 18R, 20S, 21R configuration are formed rather than the 18R, 20R, 21R isomer postulated on the basis of examination of1H‐NMR spectra. The spectra appears to be consistent with the major component of the mixture. The 20S configuration observed is in agreement with the chirality assigned to the degradation product obtained when the same alkaline solution of aldosterone is subjected to reflux. The crystals of (V) are monoclinicP21,Z= 4 witha= 20.891(2),b= 6.3848(5),c= 16.067(2)Å, β = 122.09°(1) with two molecules in the asymmetric unit. Molecule A has the 20S,21S configuration and the molecules in the second site are a mixture of the 20S, 21S and 20S, 21R configuratio

ISSN:0899-0042    

DOI:10.1002/chir.530030112

出版商:Wiley‐Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe synthesis of several 2‐alkoxy‐5‐alkyl‐tetrahydrofurans is of interest in our investigations of structure–function relationships of chiral flavour compounds. For the preparation of the enantiomeric acetals the unambiguous configurational assignment of thecisandtransseries of these compounds is indispensable. By means of crystalline acetal derivatives the absolute structure of a model compound in thecisand thetransconfiguration is revealed by X‐ray measurement and correlated with the correspondingcisandtransconfigurated aroma compounds. The first complete structure elucidation of the class of 2‐alkoxy‐5‐alkyltetrahydrofurans has

ISSN:0899-0042    

DOI:10.1002/chir.530030113

出版商:Wiley‐Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA highly stereospecific synthesis of the title compound (2R,8R)‐8‐methyl‐2‐decanol (I) has been devised via 16 simple steps. The required chirons (5 and 11) were prepared from easily accessible templates viz. (R)‐methyl citronel‐late and (S)‐glutamic acid. This on Grignard coupling furnished the ketal (12) which was converted to the desired epoxide (14) and subsequently reduced to furnish the alcohol (2R,8R)‐I. Its corresponding (2S)‐epimer was prepared by total stereoselective inversion of its C‐2 center. The title compounds are the parent alcohols of the pheromone components of t

ISSN:0899-0042    

DOI:10.1002/chir.530030114

出版商:Wiley‐Liss, Inc.    

年代:1991

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530030115

出版商:Wiley‐Liss, Inc.    

年代:1991

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530030101

出版商:Wiley‐Liss, Inc.    

年代:1991

数据来源: WILEY