Lithium diorganocuprate reagents

If conjugate addition of an organometallic nucleophile is desired, this can be accomplished by using a lithium diorganocuprate reagent, which has the organic group at-... 

In an effort to demonstrate the synthetic utility of vinyliodonium salts, small-scale reactions of (4-rm-butyl-1 -cyclohexenyl)phenyliodonium tetrafluoroborate (62) with various nucleophilic species, especially copper(I) reagents, have been conducted125,126. The copper(I)-assisted reactions include the conversions of 62 to 1-cyano-, 1-halo-, 1-alkyl- and 1-phenyl-4-ter r-butylcyclohexenes (equation 215). The alkylation and phenylation of the cyclohexenyl ligand in 62 with lithium diorganocuprates is noteworthy, since the treatment of 62 with H-butyllithium leads to fragmentation of the iodonium ion and affords only a 0.2% yield of 1 -w-butyl-4-terr-butylcyclohexene (equation 216)126. 

Conjugate addition to an a,3-unsaturated carbonyl compound is achieved routinely by using a lithium organocopper reagent or a copper-catalyzed Grignard reaction. " It should be noted that in many of these examples, and in particular in the case of lithium diorganocuprates, the resultant enolate has... 

Organoboranes, 228, 230-233 Organocopper compounds. See Lithium diorganocuprates Organolithium reagents basicity of, 551-553, 570 preparation of, 549-550, 571 reaction of... 

Early observations that certain Grignard reactions could be catalyzed by copper salts eventually led to systematic studies of organocopper compounds as reagents for carbon-carbon bond formation. Of these, lithium diorganocuprates known as Gilman reagents proved to be the most effective. 

Metallocarbenes have been implicated in the iridium-catalysed isomerization of branched hydrocarbons, such as that of 2-methylpentane (1) to 3-methylpentane (3). Studies with C-labelled (1) support a mechanism which proceeds via (2) as intermediate. Polymer-bound triphenylphosphine-lithium diorganocuprates may offer advantages in the Wurtz-type coupling of alkyl halides, in that work-up is easier and the product is not contaminated with residual tertiary phosphine. However, yields in general are comparable with those from the corresponding homogeneous reagents. ... 

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