Squaramide–Sulfonamide Organocatalyst for Asymmetric Direct Vinylogous Aldol Reactions

Asymmetric direct vinylogous aldol reactions of furan-2(5H)-one with aldehydes in the presence of a catalytic amount of novel squaramide–sulfonamide organocatalyst resulted in the corresponding addition products with high to excellent enantioselectivities. This is the first successful report illustrating an example of highly stereoselective reactions using a squaramide–sulfonamide organocatalyst.