AbstractPhotosensitized oxygenation of 19‐norsteroids with a 5–6 double bond proceeds with high stereoselectivity to give, after reduction of the initially formed hydroperoxides, 5α‐hydroxy 6‐enes as the major products. Higher amounts of 6β‐hydroxy 4‐enes, the minor products, are formed than in the case of cholesterol. These results are in agreement with the “ene” mechanism proposed bySchenckandNickonand not with the peroxirane mechanism propose