Enantioselective Mannich reaction of γ-malonate-substituted α,β-unsaturated esters with N-Boc imines catalyzed by chiral bifunctional thiourea-phosphonium salts

A novel enantioselective Mannich reaction of gamma-malonate-substituted alpha, beta-unsaturated esters with N-protected arylaldimines was realized by using asymmetric phase-transfer catalysis (APTC). With amino acid-derived bifunctional thiourea-phosphonium salts as a catalyst, a series of enantio-enriched Mannich products could be synthesized under very mild and simple reaction conditions with high yields and enantioselectivities. (C) 2019 Elsevier Ltd. All rights reserved.