Catalytic Enantioselective Allylation of Ketoimines
journal contributionposted on 14.06.2006, 00:00 by Reiko Wada, Tomoyuki Shibuguchi, Sae Makino, Kounosuke Oisaki, Motomu Kanai, Masakatsu Shibasaki
A general catalytic allylation of simple ketoimines was developed using 1 mol % of CuF·3PPh3 as catalyst, 1.5 mol % of La(OiPr)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 LiOiPr as the cocatalyst produced higher enantioselectivity and reactivity than La(OiPr)3. Thus, using the CuF−cyclopentyl−DuPHOS complex (10 mol %) and LiOiPr (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 LiOiPr accelerates the reaction by increasing the concentration of an active nucleophile, allylcopper.