Cu(I)-Mediated Intramolecular Conjugate Addition of Alkenyltrimethylstannane Functions to α,β-Unsaturated Ketones: A Convenient Preparation of Functionalized cis-Fused Bicyclo[4.3.0]non-8-en-3-ones and Bicyclo[3.3.0]oct-6-en-3-ones

A new copper(I)-mediated method for effecting intramolecular conjugate addition of alkenyl functions to α,β-unsaturated ketone systems is reported. Treatment of the substrates 14, 15, 19–21, 22 and 23 with 2.5 equiv. of CuCl in DMF at room temperature affords excellent yields of the corresponding bicyclic ketones 24, 25, 29–31, 32 and 33. On the other hand, treatment of substances 15–18 with CuCN in DMSO at 60°C provides good-to-excellent yields of the corresponding bicyclic products 25–28.