A synthesis of new groups of bicyclic steroids with a bicycle [3.3.1.] nonane ring A system is described. The insertion of an additional ring is performed by means of the Bichael addition of ethyl acetoacetate to 17~ -propionoxyandrosta -1.4.6-triene-3-one (1). followed by an aldol condensation of intermediate 17p -propionoxy-1 -(l%-carboxyethylo-2'-oxopropane)-androsta-4,6-diene-3-one (2) to give 17/3 -propionate of u(l'),
ng derivatives of 2 an oxaadamantane steroid (1-oxatricyclo 3.3.1.1 ' nonane ring A system): 17ppropionate of ld(l'), 3d (3')-propano-2'5d -epoxyandrosta-3/3, 17/3-diol @) was obtained from 2, &. and &. The synthesis of s provides the example of an intramolecular addition of a hydroxyl group to a double bond in a neutral medium. Hydrogenating conditions and a favorable stereochemistry seem necessary for this reaction. Among bridged steroids those with a bridged D-ring have been most frequently studied'. some attention has been given also to steroids with a bridge connecting rings A and B '.Steroids with a carbon -bridged ring A are much less represented in the literature. A meaningful contribution to the research in this area was made by Yates et al. 3 by obtaining steroids with a bicycle c2.2.11 heptane ring A system and by Nagata et al. octane 4 and bicycle [2.2.215