Asymmetric mannich synthesis of β-amino acids with two new stereogenic centers at the α and β positions

Article abstract of DOI:10.1002/anie.199703861

α-Branched β-amino acids 1 with erythro configuration can be made selectively and with high asymmetric induction by the reaction of O-pivaloyl-protected N-galactosylaldimines 2 with prochiral bissilyl) ketene acetals 3. The corresponding reaction with the prochiral lithium ester enolate 4 exclusively leads to the threo-configured β-amino acid derivatives.