Ruthenium-catalyzed Oppenauer-type oxidation of 3 beta-hydroxy steroids. A highly efficient entry into the steroidal hormones with 4-en-3-one functionality

Oxidation of 5-unsaturated 3 beta-hydroxy steroids 1 to the corresponding 4-en-3-one derivatives 2 can be performed efficiently by acetone at reflux in the presence of a catalytic system consisting of either (PPh(3))(3)RuCl2 (3) and K2CO3 or [(C(4)Ph(4)COHOCC(4)Ph(4))(mu-H)][(CO)(4)Ru-2] (4). The reaction proceeds via a ruthenium-catalyzed dehydrogenation of 1 and subsequent hydrogen transfer to acetone with concomitant double bond migration.