Chemistry of Higher Order, Mixed Organocuprates. 5. On the Choice of the Copper(I) Salt for the Formation of R2CuLi

Article abstract of DOI:10.1021/jo00152a026

Chemical and spectroscopic studies are presented that have been designed to manifest differences in reagent composition and reactivity between mixtures of CuI/2RLi and CuSCN/2RLi.The results indicate that while both Cu(I) salts are reported to serve as precursors to lower order cuprates R2CuLi, CuSCN may actually be forming a higher order, mixed species R2Cu(SCN)Li2.This would explain the discrepancy in coupling reactions of each solution with similar organic substrates under otherwise identical conditions.The presence of added lithium salts demonstrates that while Li I added to CuSCN/2RLi has essentially no effect, introduction of an equivalent of LiSCN to CuI/2RLi dramatically alters the efficiency of ligand transfer.