Joseph A. Kozlowski

More highly mixed, higher order cyanocuprates “RT(2-thienyl)Cu(CN)Li2”. Efficient reagents which promote selective ligand transfer

Abstract The combination of an organolithium (R T Li) and 2-lithiothiophene (2-thienyl) with CuCN forms a new reagent, “R T (2-thienyl)Cu(CN)Li 2 .” This species selectively transfers the R T ligand in substitution reactions with epoxides and halides. In conjugate addition processes, the cuprate reacts with unhindered substrates, while β,β-disubstituted cases unexpectedly afford products resulting from 1,2-addition of the thiophene group. The prospects for use of these reagents in the synthesis of polyene macrolide antibiotics are discussed.

Effects of Lewis acids on higher order, mixed cuprate couplings

Abstract The presence of BF 3 ·Et 2 O in reactions of R 2 Cu(CN)Li 2 and R T (2-thienyl)Cu(CN)Li 2 with epoxides and α,β-unsaturated ketones leads to dramatic enhancements in reaction rates and/or product yields relative to those observed in the absence of this lewis Acid.

Chemistry of higher order, mixed organocuprates. reactions of α,β-unsaturated ketones.

Abstract Organocuprates of general formula R 2 Cu(CN)Li 2 react rapidly with α,β-unsaturated ketones at low temperatures and in high yields to deliver ligands in a conjugate manner. These reagents apparently do not require the use of additives for stabilizing or solubilizing purposes.

Further insight into lower order cuprate chemistry; On the use of CuBr·Me2S vs CuI enroute to R2CuLi

Abstract Both 1 H and 7 Li NMR experiments show that 2MeLi + either CuBr·Me 2 S or CuI in THF afford the same species, Me 2 CuLi (+ LiX). However, use of the former source of Cu(I), depending upon its purity and especially handling, can lead to significantly decreased chemical yields. The reasons behind these observations and the implications for cuprate couplings are discussed.

Ligand mixing in lower order organocuprates: synthetic, mechanistic, and structural implications

Abstract NMR spectroscopic evidence attesting to facile ligand exchange between lower order cuprates in THF and Et2O solution is discussed. A mechanistic pathway is suggested to account for ligand redistribution in THF. A dimeric model for R2CuLi is supported by the spectral data.