Stereoselective synthesis and hormonal activity of novel dafachronic acids and naturally occurring steroids isolated from corals

A stereoselective synthesis of (25S)-Delta(1)-, (25S)-Delta(1,4)-, (25S)-Delta(1,7)-, (25S)-Delta(8(14))-, (25S)-Delta(4,6,8(14))-dafachronic acid, methyl (25S)-Delta(1,4)-dafachronate and (25S)-5 alpha-hydroxy-3,6-dioxocholest-7-en-26-oic acid is described. (25S)-Delta(1,4)-Dafachronic acid and its methyl ester are natural products isolated from corals and have been obtained by synthesis for the first time. (25S)-5 alpha-Hydroxy-3,6-dioxocholest-7-en-26-oic acid represents a promising synthetic precursor for cytotoxic marine steroids.