Re-evaluation of Organocuprate Reactivity: Logarithmic Reactivity Profiles for Iodo- versus Cyano-Gilman Reagents in the Reactions of Organocuprates with 2-Cyclohexenone and Iodocyclohexane

Iodo-Gilman reagents Me2- CuLi · LiI, Bu2CuLi · LiI, and BuThCu- Li · LiI and cyano-Gilman reagents (nee "higher order cyanocuprates" Me2Cu- Li · LiCN, Bu2CuLi · LiCN, and BuTh- CuLi · LiCN react with 2-cyclohexenone at various rates, which depend upon the R groups (Me, Bu, Tha thienyl), Li salt (LiI vs. LiCN), solvent (ether vs. THF), and amount of trimethylsilyl chloride (TMSCl) additive. The effect of the Li salt (CuI vs. CuCN precursor) is less than that of solvent or TMSCl. The butylcuprate-iodocyclohexane reaction has also been examined as a function of Li salt, solvent, and TMSCl additive, and similar effects are observed. The reactivity matrix R with elements ri,j is a convenient way to store and present a large amount of relative reactivity data. Entry ri,j is the ratio of the rate with reagent i to the rate with reagent j, which we approximate by using yields meas- ured after a short time (4 s). The loga- rithmic reactivity profile (LRP) pro- vides an efficient means for determining yields under conditions where such comparisons are valid. The results of a large number of 4-point LRPs and related reactions are tabulated and an- alyzed to provide a clearer picture of organocuprate reactivity.