Catalytic Asymmetric Direct Mannich Reactions of Carbonyl Compounds with α-Imino Esters

The development of a direct catalytic asymmetric Mannich reaction is shown and its potential demonstrated by the synthesis of optically active lactones via 4-hydroxyglutamic acid ester derivatives. The catalytic asymmetric Mannich reaction of carbonyl compounds with α-imino esters [Eq. (1); Ts = p-toluenesulfonyl] gives good yields and diastereoselectivities, as well as excellent enantioselectivities.