Transfers cuprate

The procedure described here illustrates the preparation of mixed lithium arylhetero(alkyl)cuprate reagents and their reactions with carboxylic acid chlorides,4 These mixed cuprate reagents also react with a,a -dibromoketones,12 primary alkyl halides,4 and a,/3-unsaturated ketones,4 with selective transfer of only the alkyl group. 

Scheme 36). Interestingly, the higher order cuprate 206 underwent conjugate addition with only moderate selectivity. This is likely due to the intervention of an electron transfer pathway. Competing electron transfer reactions involving a-alkoxymetal reagents of this type have also been reported by Cohen [81]. 

Figure 8.6 Schematic depiction of a cuprate superconductor. Doping into the charge reservoir layers results in the transfer of holes to the superconducting layers.

Vinyl cuprates.17 Vinyl cuprates can be prepared conveniently by in situ trans-metallation of vinylstannanes, available by hydrostannylation of alkynes, with a cuprate such as (CH3)2Cu(CN)Li2 (equation I). Reagents prepared in this way effect conjugate addition of the vinyl group to an enone with essentially no transfer of the methyl group. 

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