Asymmetric synthesis of warfarin and its analogs catalyzed by C2-symmetric squaramide-based primary diamines

Abstract

Novel C₂-symmetric N,N′-bis(2-amino-1,2-diphenylethyl)squaramides with 1,2-di(pyridin-2-yl)ethane and 1,2-diphenylethane spacer groups were designed and applied as organocatalysts in asymmetric additions of 4-hydroxycoumarin and 4-hydroxy-6-methyl-2H-pyran-2-one to α,β-unsaturated ketones.