17α-Hydroperoxypregnenes. IV. A Comparative Study of their Fragmentation by Electron Impact and High Temperature Chromatography

The fragmentation of 17α-hydroperoxypregnenolone and 17α-hydroperoxyprogesterone by electron impact and thermolysis is described. It is shown that the fragmentation pattern follows a common pathway for both compounds, determined exclusively by the substituents at ring-D. A new reaction in steroid chemistry, termed deoxygenation, is discovered and its mechanism explained by intramolecular hydrogen abstraction via a six-membered cyclic transition state involving the 20-ketone group.