Stereospecific cis-reduction of hexahydro-3-oxophenanthrene derivatives. Total synthesis of a new class of ring-C aromatic steroid

Abstract

Catalytic hydrogenation (Pd/C, 10%) of the hexahydro-3-oxophenanthrene (2a) in acidic medium gave the trans-fused octahydrophenanthrene ring system (5b) predominantly, whereas reduction of (2a–c) with LiAlH₄ followed by oxidation gave exclusively the cis-fused systems (4a), (4c), and (4e), respectively; the products (4a) and (5b) have been elaborated to the 10βH and 10αH isomers, respectively, of 5,12-dimethyl-5β- gonane-8,11,13-triene-17-one.