Chemical and Spectroscopic Studies on Copper Iodide Derived Organocuprates: New Insight into the Composition of Gilman's Reagent

Article abstract of DOI:10.1021/ja00297a027

Both 1H and 7Li NMR spectroscopy at high field have served to reveal that the addition of ethereal MeLi to MeCu/THF, in the absence of LiI, leads to unprecedented equilibria (K_eq ca. 11) between Me2CuLi and MeLi plus Me3Cu2Li.From a series of spectra at -70 degC, a scheme is proposed to account for the signals observed in solutions of varying MeLi:MeCu ratios.These data lead to the conclusion that not only Gilman's reagent but also "Me3CuLi2" and "Me5Cu3Li2" are not discrete, but rather are composed of differing percentages of the same components.In the presence of LiI, or in Et2O solutions alone, however, this equilibrium does not exi sts for MeLi:MeCu ratios up to 1:1.Chemical tests on both ketones and esters, as well as a series of Gilman tests, fully corroborate the existence of various forms of Gilman's reagent.