A HIGH YIELDING SYNTHESIS OF (25R)-SPIRO[CYCLOPROPANE-1,2'-(19-NOR-SPIROST-4-EN-22-ALPHA-O)-3-ONE]

Abstract

The synthesis of title compound (1) by a series of functional group transformations in a high overall yield from the commercially available diosgenin is described. The synthesis requires 5-alpha, 6-beta-bromohydrin formation, radical-initiated ring formation, regioselective opening of the epoxy ring, and regioselective cyclopropanation as crucial steps.