Enantioselective organocatalytic amine conjugate addition

The first enantioselective organocatalytic amine conjugate addition has been successfully developed. The application of LUMO-lowering iminium catalysis has enabled the highly chemo- and enantioselective 1,4-addition of a rationally designed N-silyloxycarbamate nucleophile (HOMO-raised) to α,β-unsaturated aldehydes. Imidazolidinone 2•pTSA was found to catalyze the addition of various orthogonally N-protected silyloxycarbamate nucleophiles to a range of α,β-unsaturated aldehydes, affording synthetically useful β-amino aldehyde intermediates. The synthetic utility of the protocol was demonstrated in the rapid synthesis of enantioenriched β-amino acids in one operation and 1,3-amino alcohol derivatives in three operations. Copyright © 2006 American Chemical Society.