Silylcopper reagents 1,4 addition

Michael additions [112] and other reactions typical of organocopper species can also be performed with silylcopper reagents such as TBDMSCu, prepared by Sn/Cu exchange [113] between Me3SnSiMc2(tBu) and Bu(Th)CuLi LiCN (Th = 2-thienyl) (Scheme 2.53) [113, 114]. 

Several catalytic protocols have been developed for the 1,4-addition of silylcopper reagents to enones and other Michael acceptors. Lipshutz et al.183 treated phenyldimethylsilyllithium with dimethylzinc and used the silylzinc reagent PhMe2SiZnMe2Li thus formed as the nucleophile in copper-catalyzed 1,4-additions to various enones and enals, for instance, verbenone 248 which afforded the desired product 249 in almost quantitative yield (Equation (14)). Interestingly, the rather slow addition reaction is strongly accelerated by catalytic amounts of scandium triflate. 

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