BINOL–quinine–squaramides as efficient organocatalysts for the asymmetric Michael addition of 2-hydroxy-1,4-naphthoquinone to nitroalkenes
摘要:
A set of BINOL-quinine-squaramides were synthesized, and then used as organocatalysts to promote the catalytic enantioselective Michael addition reaction of 2-hydroxy-1,4-naphthoquinone to nitroalkenes with excellent yields and ees (up to 99% yield and 93% ee) at low catalyst loading (0.5 mol %). (C) 2013 Elsevier Ltd. All rights reserved.