Synthesis of β-difluorine-containing amino acids

A convenient strategy was developed to prepare several β-difluoroamino acids. As exemplified by the synthesis of 3,3-difluoro- -homocysteine, 3,3-difluoro- -homoserine and 3,3-difluoro- -methionine, the reaction sequence all started from -isoascorbic acid. This approach holds potential to be extended to make other β-difluorine-containing amino acids.