Journal of the American Chemical Society, Vol.128, No.23, 7687-7691, 2006
Catalytic enantioselective allylation of ketoimines
A general catalytic allylation of simple ketoimines was developed using 1 mol % of CuF(.)3PPh(3) as catalyst, 1.5 mol % of La((OPr)-Pr-/)(3) as the cocatalyst, and stable and nontoxic allylboronic acid pinacol ester as the nucleophile. This reaction constituted a good template for developing the first catalytic enantioselective allylation of ketoimines. In this case, using (LiOPr)-Pr-i as the cocatalyst produced higher enantioselectivity and reactivity than La((OPr)-Pr-i)(3). Thus, using the CuF-cyclopentyl-DuPHOS complex ( 10 mol %) and (LiOPr)-Pr-i ( 30 mol %) in the presence of tBuOH (1 equiv) produced high enantioselectivity up to 93% ee from a range of aromatic ketoimines. Mechanistic studies indicated that (LiOPr)-Pr-i accelerates the reaction by increasing the concentration of an active nucleophile, allylcopper.