Abstract

A newly chiral tertiary amine-squaramide has successfully developed and applied into the asymmetric Michael addition of 4-hydroxycoumarin to β,γ-unsaturated α-ketoesters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of coumarin derivatives were obtained with good yields and enantioselectivities.

Keywords: Coumarin derivatives, Michael addition, organocatalysis, squaramides, β, γ-unsaturated α-ketoesters, 4-hydroxycoumarin.