Synthetic approaches to 19-norsteroids

6β-Acetoxy-3β-benzyloxy-5α-androstan-5-ol-17-one (51), prepared from androstenolone, underwent Westphalen rearrangement to give the 5β-methyl-Δ9(10)-compound. Lead tetraacetate functionalisation of the 5β-methyl group in the 3β-hydroxyl derivative (53) gave 6β-acetoxy-3β,5-oxaethano-19-nor-5β-androst-9(10)-ene-17-one. Westphalen rearrangement of 6β-cyano-3β-methoxy-5α-cholestan-5-ol (56) cave the 6β-cyano-5β-methyl-derivative (57). Hofmann–Löffler cyclisation of the 6β-N-chloro-N-ethylamino-methyl derivative (62), prepared from this cyano-compound (57), cave none of the anticipated cyclic product (63), but, instead, the products were deduced as being mainly dimeric species (68 and/or 69), in which the 5β-methyl group had probably been functionalised. [Continues.]