Lithium alkynylcuprates

Boche and coworkers described high-yield conversion of lithium alkynylcuprates to aUcynylamines using 4c as amination reagent (Scheme 41) ". 

Lithium alkynylcuprates react with haloallenes to give similar skipped diacetylenes (see below). The related skipped enynes can be prepared by treatment of (pentadienyl)iron(tricarbonyl) halide complexes with dilithium trialkynylcuprates, the compounds being isolated as the iron(tricarbonyl)(diene) complexes (Scheme 4). Further examples of alkylation reactions of copper alkynides are illustrated in Scheme 5. Reaction between a lithium cyanoaikynecuprate and an iodoallene leads to a skipped diacetylene. This useful reaction has been used by Corey in his synthesis of hybridalactone (Scheme 6). °... 

Boche and coworkers also reported that coupling of 1-alkynyl carbanions with N,N-dialkylamino groups could be achieved in preparing higher-order lithium 1-alkynylcuprates and they used 3h as the amination reagent (Scheme 25). ... 

Not surprisingly, when only hard substituents are present in the cuprates, the reaction with a,y3-unsaturated ketones takes a different course. Thus, lithium tri-alkynylcuprates add to the carbonyl selectively (49). 

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