A synthetic approach to the C/D ring system of steroids

Abstract

This thesis is concerned with an approach to the synthesis of the C/D ring system and side chain of steroids with 11-oxygen functionality. (+)-9,10-Dibromocamphor (18) [prepared in three steps from (+)-endo-3-bromocamphor (4)] was converted to the diester 144 in six steps. The diester 144 underwent a modified acyloin reaction to provide the silylated enediolate 154. A novel methanolysis of the acyloin intermediate 154 gave a 1:1 mixture of the isomeric tricyclic methoxy-ketones 168 and 176. Oxidative cleavage of these methoxyketones 168 [Formula Omitted] and 176 provided the isomeric aldehydes 178 and 180 which were then transformed into the corresponding isomeric esters 181 and 182. This represents a synthesis of the C/D ring system of steroids with 11-oxygen functionality and establishment of the correct absolute stereochemistry at C(13) and C(17). [Formula Omitted]