Partial synthesis of a marine secosterol from Gersemia fruticosa: Preparation of the intermediate precursor 3 beta ,6 alpha -diacetoxy-24-methyl-12-oxo-5 alpha -chol-9,11-en-24-oate

The conversion of desoxycholic acid (2) into the title compound 14 by 13 respectively 17 steps is described herein, including stereoselective construction of C-3 and C-6 hydroxy moieties and introduction of a Delta super(9,11) double bond by dehydrogenation. 14 is believed to serve as a putative precursor for the synthesis of secosterol 1, isolated from the soft coral Gersemia fruticosa.