Synthesis of 7-substituted-5-androstene derivatives promoted by SmI2

The 7-substituted-5-androstene derivatives 2a-10a and 2b-10b were prepared by reaction of 3β,17β-di(tert-butyldimethylsilyloxy)-5-androsten-7-one 1 with different organic halides. The resulting 7α- and 7β-isomers were carefully separated by column chromatography. The structural assignments of the 7α- and 7β-isomers were determined by 13C-NMR.