Synthesis of β-amino esters by the conjugate addition of nitrogen nucleophiles to α,β-unsaturated esters having chiral p-tolylsulfinyl groups

The conjugate addition of nitrogen nucleophiles to t-butyl (E)-2-(p-tolylsulfinyl)cinnamates (1) afforded the corresponding chiral β-amino esters, which are important building blocks for synthesis of biologically active polyamine alkaloids. The diastereoselectivity of the reactions was 49 to 89%, and (S)-β-amino esters were obtained from (R)-1 while (R)-β-amino esters were synthesized from (S)-1, respectively.