Reactivity of steroidal dienes towards the methyltrioxorhenium/H2O2-urea oxidation system: isolation and characterization of new oxygenated steroids

To examine the reactivity of conjugated diene steroids towards methyltrioxorhenium (MTO)-catalysed oxidation with the urea-hydrogen peroxide adduct (UHP) and its possible use in functionalization of the rings of the steroid nucleus, the reactions of the MTO/UHP system with cholesta-3,5-diene (4) and 5a-cholesta-7,9(11)-dien-3 beta -yl acetate (13) in aprotic solvents were investigated. The structures of all new steroids were verified on the basis of chemical evidence and interpretation of spectroscopic data including H-H COSY, HMBC, and HMQC experiments