Asymmetric synthesis of β-amino esters by aza-michael reaction of α,β-unsaturated amides using (S,S)-(+)-pseudoephedrine as chiral auxiliary

Chiral nonracemic beta-amino esters were prepared in good yields and enantioselectivities using the diastereoselective conjugate addition of nitrogen nucleophiles to alpha,beta-unsaturated amides derived from (SS)-(+)-pseudoephedrine as the key step. In this way, several Beta-amino amide adducts were prepared using different conjugate acceptors and two different lithium benzylamides as nucleophiles. These adducts were easily converted in only one step, into the final, highly enantioenriched beta-amino esters.