Progress in Partial Synthesis of a Marine Secosterol from Gersemia fruticosa: Preparation of the Steroidal Core Unit

Abstract

The synthesis of the requisite protected steroidal core unit 13 en route to secosterol 1, a cytotoxic constituent of the soft coral Gersemia fruticosa, is described. The conversion of the intermediate precursor 3 into 13 succeeds through oxidative side chain degradation, deoxygenation of C-12 via reductive desulfurization and cleavage of the C-ring moiety by ozonolysis.