Photochemically induced oxidation of some steroidal isoxazolidines by molecular oxygen

Abstract

U.v. irradiation of the steroidal isoxazolidines 5α,10α-imino-oxy-5(10 → 1βH)abeo-5α-cholestan-3β-olacetate (1a) and the corresponding N-methyl and N-acetyl derivatives (1b) and (1c) in various solvents in the presence of oxygen, gave the nitro products (2), (3), and (4) and the azoxy products (5) and (6); a mechanism involving exciplex formation followed by proton transfer from isoxazolidine to molecular oxygen is proposed.