New, Scalable Route for the Synthesis of a trans-Fused Hexahydro-1H-phenanthren-2-one from a Conjugated Tetrahydro-3H-phenanthren-2-one

Abstract A three-step, readily scalable route for the conversion of a ring-conjugated tetrahydro-3H-phenanthren-2-one to a trans-fused hexahydro-1H-phenanthren-2-one is described. The key step is the hydrogenation of a double bond using a nearby ketal moiety to assist in the stereoselective delivery of the hydrogen.