Chiral cyclopropenimine-catalyzed enantioselective Michael additions between benzophenone-imine of glycine esters and ,-unsaturated pyrazolamides

A highly enantioselective Michael addition between benzophenone-imine of glycine esters and beta-substituted alpha,beta-unsaturated pyrazolamides has been realized by using 10 mol% of a chiral cyclopropenimine (Lambert catalyst, CSB-1) as an organosuperbase catalyst under very mild conditions to afford Michael adducts in up to 95% yield and 99% ee. The pyroglutamic acid esters with two adjacent stereocenters are obtained through subsequent lactamization in quantitative yields and excellent enantioselectivities. A highly chiral cyclopropenimine-catalyzed enantioselective Michael addition between benzophenone-imine of glycine esters and beta-substituted alpha,beta-unsaturated pyrazolamides has been realized to afford Michael adducts in up to 95% yield and 99% ee.