ORGN 131

Studies in our laboratory have shown that the intramolecular cyclization reactions of ethoxycarbonyl and acyl derivatives of g and d hydroxysulfones is a convenient method for the preparation of lactones, dihydropyrans and dihydrofurans. For this methodology to have wider synthetic application, convenient routes for the stereoselective preparation of hydroxysulfones are required. We have recently developed direct methods for the stereoselective incorporation of g and d hydroxysulfone units onto readily available cyclic precursors. The ethoxycarbonyl and acyl derivatives of these hydroxysulfones have been shown to undergo useful annulation chemistry leading to bicyclic lactones, dihydrofurans and dihydropyrans with stereochemical control. The chemistry described should be readily amenable to the preparation of a wide variety of polycyclic ring systems of biological interest.