Stereoselective synthesis of rac-(8R,13S,14S)-7-oxa-estra-4,9-diene-3,17-dione

The first synthesis of a novel oxa-steroid, rac-(8R,13S,14S)-7-oxa-estra-4,9-diene-3,17-dione has been achieved via stereoselective catalytic hydrogenation of the tetra-substituted indene intermediate, whose structure was confirmed by X-ray crystallography. In contrast to the previous reports of similar indene systems, it was found that catalytic hydrogenation of indenes with a large substituent at the C-2 position and a bulky β-oriented protective group at the C-6 position resulted in cis-indanes instead of trans-indanes.