Gilman-Type versus Lipshutz-Type Reagents: Competition in Lithiocuprate Chemistry

CuCN reacts with RLi and TMPLi (TMP = 2,2.6,6-tetramethylpiperidide) to give Gilman-type cuprates R(TMP)CuLi.nL (R = Ph, n = 3, L = THF 2; R = Me, n = 1, L = TMEDA 3). 3 and 3.LiCN have been tested in directed ortho cupration with data suggesting enhanced efficiency for Lipshutz-type 3.LiCN; competition between Lipshutz- and Gilman-type formulations is rationalized by DFT methods.