Enantioselective organocatalytic Michael addition of aldehydes to nitroethylene:: Efficient access to γ2-amino acids

Enantioselective organocatalytic Michael addition of aldehydes to nitroethylene catalyzed by (S)diphenylprolinol silyl ether provides beta-substituted-delta-nitroalcohols in nearly optically pure form (96-99% ee). The Michael adducts bear a single substituent adjacent to the carbonyl and can be efficiently converted to protected Y(2-)amino acids, which are essential for the systematic conformational studies of Y-peptide foldamers.