Synthesis of (±)-hamigeran B, (-)-hamigeran B, and (±)-1-epi-hamigeran B:: Use of bulky silyl groups to protect a benzylic carbon-oxygen bond from hydrogenolysis

Enone 42 was converted into diene 56, which was then subjected to hydrogenation. Use of the tert-butyldimethylsiloxy groups enforces facial selectivity and protects the C(5) oxygen from hydrogenolysis. The resulting product (55) is easily converted into hamigeran B (1), a marine natural product with powerful activity against herpes and polio viruses. Optically pure enone 73 was made by use of a Meyers' auxiliary and converted into (-)-hamigeran B with the natural absolute configuration.