Stereospecific Total Synthesis of the Antiviral Agent Hamigeran B—Use of Large Silyl Groups to Enforce Facial Selectivity and to Suppress Hydrogenolysis

Stereoselective hydrogenation of the tetrasubstituted double bond in enone 1 is possible, provided the keto group at C7 is first removed and the α face is blocked by tert-butyldimethylsiloxy groups at positions 10 and 11. The resulting product 2 is easily converted into hamigeran B (3), a marine natural product with powerful activity against herpes and polio viruses. Si*=tBuMe2Si.