Regioselective Addition of Stannylcyanocuprates to Acetylenic Ethers: A Chemical and Spectroscopic Study

The reactions of acetylenic ether (1) with higher order cuprates (2a), (2b) and (2c) were studied chemically and spectroscopically. Conditions were developed to efficiently and regioselectively prepare α- and β-stannylvinyl ethers. 1 H and 13 C NMR studies of these reactions suggest that in the presence of HMPA, higher order stannylcyanocuprate, (Bu 3 Sn) 2 Cu(CN)Li 2 , (2a), exists in equilibrium with Gilman cuprate, (Bu 3 Sn) 2 CuLi