A new approach toward the synthesis of C,D-cis coupled steroid and C,D-cis coupled D-homosteroid skeletons

A short and efficient procedure has been developed for the synthesis of C,D-cis coupled steroid and D-homo steroid skeletons. A Mukaiyama reaction with transfer of the silyl group of the starting silyl enol ether to the enol of the adduct followed by addition of vinyl magnesium bromide to the unprotected carbonyl group leads to adducts which can be cyclized with ZnBr2. The synthesis of functionalized steroid skeletons in overall yields of about 50% in four steps can be achieved in this way. (C) 2003 Elsevier Science Ltd. All rights reserved