Gilman cuprates, reactions with alkyl halides

Work in the reactions of alkyl halides with the more conventional Gilman cuprates has slackened considerably. Synthetically, alkylations have been performed employing alkynes as the second, disposable ligand in cuprates. In the transfer of vinyl groups, this allows aminomethylation or thiomethylation without the addition of HMPA or triethyl phosphite and without loss of alkene geometric integrity (equation 10)14. The addition of pentynylcopper to a-lithiated formamidines allows alkylation with primary alkyl iodides (equation ll)15. 

Another transition metal-catalyzed carbon-carbon bond-forming reaction we shall discuss is the Corey—Posner, Whitesides-House reaction. Using this reaction an alkyl halide can be coupled with the alkyl group from a lithium dialkyl cuprate reagent (often called a Gilman reagent). This reaction does not have a catalytic mechanism. 

The Corey—Posner, Whitesides—House reaction involves the coupling of a hthium dialkyl-cuprate (called a Gilman reagent) with an alkyl, alkenyl, or aryl halide. The alkyl group of the lithium dialkylcuprate reagent may be primary, secondary, or tertiary. However, the halide with which the Gilman reagent couples must be a primary or cychc secondary alkyl halide if it is not alkenyl or aryl. 

Some reactions of the Gilman reagent with an alkyl halide occur in two steps, not by an Sj 2 mechanism. A two-step sequence occurs when a dialkyl cuprate reacts with an alkyl iodide. 

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