Thiophosphoramide catalyzed asymmetric Michael addition of acetone to functionalized nitrostyrenes: a convenient approach to optically active tetrahydropyrans

Thiophosphoramide 5d was found to be an effective organocatalyst for the enantioselective Michael reaction of problematic acetone to various hydroxymethyl nitrostyrenes, affording the multisubstituted tetrahydropyrans with three stereogenic centers. The Michael addition products generated were obtained as a single diastereomer with enantioselectivities ranging from 46% to 74% ee.