Organocuprates addition reactions

Like other carbon-carbon bond forming reactions organocuprate addition to enones is a powerful tool m organic synthesis... 

Reactions of highly electron-rich organometalate salts (organocuprates, orga-noborates, Grignard reagents, etc.) and metal hydrides (trialkyltin hydride, triethylsilane, borohydrides, etc.) with cyano-substituted olefins, enones, ketones, carbocations, pyridinium cations, etc. are conventionally formulated as nucleophilic addition reactions. We illustrate the utility of donor/acceptor association and electron-transfer below. 

Copper has long played a dominant role in stoichiometric organometallic reactions in synthesis. Organocuprate mediated conjugate addition reactions are a cornerstone of carbon-carbon bond-forming reactions. Its preeminence has not been overlooked in the search for asymmetric versions of the reaction (134-136). However, the requirement for stoichiometric amounts of the metal has dampened efforts to introduce chirality into this process. 

Subsequently, Corey and coworkers40 42 described nucleophilic addition reactions of organocopper reagents and organocuprates to several acceptor-substituted dienes. The... 

As in the case of addition reactions of carbon nucleophiles to activated dienes (Section HA), organocopper compounds are the reagents of choice for regio- and stereoselective Michael additions to acceptor-substituted enynes. Substrates bearing an acceptor-substituted triple bond besides one or more conjugated double bonds react with organocuprates under 1,4-addition exclusively (equation 51)138-140 1,6-addition reactions which would provide allenes after electrophilic capture were not observed (cf. Section IV). 

Only few examples have been reported so far on nucleophilic addition reactions to acceptor-substituted polyenes123,124,186 188. In 1933, Farmer and Martin186 examined the reaction of methyl 2,4,6-octatrienoate with sodium dimethyl malonate and isolated the 1,4-adduct as major product (equation 81). In contrast to this, 3,5,7-nonatrien-2-one and ethyl 2,4,6-octatrienoate react with organocuprates under 1,8-addition to provide the 4,6-dien-2-ones and 3,5-dienoates, respectively (equation 82)187. 

The many uses of organocuprates have been the subject of numerous reviews,1 3 4 6-10 especially the conjugate addition reaction which has received the most attention1 and is the subject of this discussion. 

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