Observations on various silyl-cuprate reagents

Abstract

The mixed silyl-cuprate reagent (6), made from 1 equiv. of methyl-lithium, 1 equiv. of phenyldimethylsilyl-lithium, and 1 equiv. of copper(I) cyanide, reacts with 3-methylcyclohexenone (7), with methyl cinnamate (9), with 1-vinylcyclohexyl acetate (11), and with hex-1-yne (13) to transfer, in each case, the silyl group, and to give the β-silylcarbonyl compounds (8) and (10), the allylsilane (12), and the vinylsilane (14), without the concomitant formation of involatile silicon-containing by-products. The silyl-cuprate reagent (15), prepared from trimethylsilyl-lithium and copper(I) cyanide, reacts with similar substrates, in the same way, even though hexamethylphosphoric triamide (HMPA) is present in the reaction medium.