Abnormal Beckmann fragmentation/ring closing metathesis route for preparation of 18-nor-Δ13(17)-androgens and their 18-nor-13,17-epoxide derivatives

The synthesis of 18-nor-Δ13(17)-androgens and the structurally related 13,17-epoxides is described. The synthetic route involves the cleavage of 17-ketosteroids by an abnormal Beckmann rearrangement, modification of the D-ring cleavage product to obtain an intermediate tricyclic diene and ring closing metathesis of the diene to the 18-nor-Δ13(17)-androgen. (3α,5α)-18-Norandrost-13(17)-en-3-ol and the derivative 13α,17α- and 13β,17β-epoxides were prepared by this route.