Reactions of Enones with the New Organocuprates, LiCu2(CH3)3, Li2Cu3(CH3)5, and Li2Cu(CH3)3
Journal
Journal of Organic Chemistry
Journal Volume
42
Journal Issue
6
Pages
1099-1102
Date Issued
1977
Author(s)
Abstract
It has been reported that a mixture of (CH3)Li and Li-Cu(CH3)2 provides unusually stereoselective methylation of 4-tert-butylcyclohexanone compared to CH3 Li alone.1 It was suggested that a highly reactive cuprate having the stoichi-ometry Li2Cu(CH3)3 or Li3Cu(CH3)4 is formed when CH3Li and LiCu(CH3)2 are allowed to react and that reaction of these species with the ketone would explain the observed results. We have recently obtained direct evidence for the existence of LiCu2(CH3)3 and Li2Cu(CH3)3 in both dimethyl ether and tetrahydrofuran and indirect evidence for the species Li2Cu3(CH3)5 and Li2Cu(CH3)3 in diethyl ether by low-tem-perature NMR.2 All of the cuprates appear to be single species in solution except Li2Cu(CH3)3 which has been shown to exist as an equilibrium mixture. Since LiCu(CH3)2 has proven to be an excellent conjugate methylating agent for α, β-unsatu-rated carbonyl compounds, it was considered to be important to evaluate these new cuprates as conjugate methylating agents. © 1977, American Chemical Society. All rights reserved.
Type
journal article