The β-keto-ester which is obtained by Dieckmann cyclization of the dimethyl ester (I) of the dicarboxylic acid obtained by oxidative opening of ring A in 5α-cholestan-3-one and related compounds has been shown to have the structure IIa, by its degradation, via the unsaturated acid (Va), to A-nor-5β-cholestan-3-one (VI) and to the dimethyl ester (VIIb). The stereochemistry of compound IIa and of related
通过对
5α-胆甾烷-3-酮中的环A氧化开环而获得的二元
羧酸的二甲酯(I)进行Dieckmann环化反应获得的β-
酮酯已显示具有结构IIa,通过不饱和酸(Va)降解为A-nor-5β-胆甾烷-3-酮(VI)和二甲酯(VIIb)。讨论了化合物IIa和相关的A-取代的A-nor-
5α-胆甾烷的立体
化学。从5α-胆甾-1-烯-3-酮(XIV)开始,合成了α-nor-5α-
胆甾醇-1-酮(XVIIb)。