Convenient, large-scale asymmetric synthesis of β-aryl-substituted α,α-difluoro-β-amino acids

The enantiopure p-toluenesulfinimines were found to be efficient as chiral imine equivalents in the high temperature Reformatsky-type additions with BrZnCF2COOEt affording an efficient approach to the enantiomerically pure α,α-difluoro-β-amino acids. High chemical and stereochemical yields (drs>9:1, and as high as 99:1) render this method immediately useful for preparing the target amino acids.