Dioxirane mediated steroidal alkene epoxidations and oxygen insertion into carbon-hydrogen bonds

Article abstract of DOI:10.1016/S0040-4039(00)79489-5

Dioxiranes generated in situ from a range of ketones afforded the 5,6-epoxides in high yield from cholesterol or its acetate. The α:β ratio was close to 1 in contrast to that observed for peroxyacids (ca. 4). 4,4-Dimethylcholesterol and its acetate were not epoxidised but were oxidised respectively to the 3,7-dioxo- and the 7-oxo-derivative respectively with dimethyldioxirane. Oxidations of steroidal alcohols were shown to proceed via an oxygen insertion mechanism by use of ¹⁸O-labelled substrates and 5α-cholestan-3α-ol was oxidised more quickly (>1.5 x) than its 3β-epimer.