Convenient Asymmetric Synthesis of β-Substituted α,α-Difluoro-β-amino Acids via Reformatsky Reaction between Davis'N-Sulfinylimines and Ethyl Bromodifluoroacetate

The enantiopure Davis' N-sulfinylimines were found to be efficient as chiral imine equivalents in the high-temperature Reformatsky-type additions with BrZnCF(2)COOEt affording an efficient approach to the enantiomerically pure alpha,alpha-difluoro-beta-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.