Editing Gilman reagent (section)

==Mixed cuprates==
More useful generally than the Gilman reagents are the so-called mixed cuprates with the formula [RCuX]<sup>−</sup> and [R<sub>2</sub>CuX]<sup>2−</sup> (see above for the controversy over existence of the latter).  Such compounds are often prepared by the addition of the organolithium reagent to copper(I) halides and cyanide. These mixed cuprates are more stable and more readily purified.<ref name=eEROS>Steven H. Bertz, Edward H. Fairchild, Karl Dieter, "Copper(I) Cyanide" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley & Sons. {{doi|10.1002/047084289X.rc224.pub2}}</ref> One problem addressed by mixed cuprates is the economical use of the alkyl group. Thus, in some applications, the mixed cuprate with the formula {{chem|Li|2|[Cu(2-thienyl)(CN)R]}} is prepared by combining thienyllithium and cuprous cyanide followed by the organic group to be transferred. In this higher order mixed cuprate, both the cyanide and thienyl groups do not transfer, only the R group does.<ref>[[Bruce H. Lipshutz]], Robert Moretti, Robert Crow "Mixed Higher-order Cyanocuprate-induced Epoxide Openings: 1-Benzyloxy-4-penten-2-ol" Org. Synth. 1990, volume 69, pp. 80. {{doi|10.15227/orgsyn.069.0080}}</ref>