The Mitsunobu reaction in the synthesis of α,α-difluoro-β-amino acids

A three-stage strategy is proposed to prepare α,α-difluoro-β-amino acids starting from aldehydes and with ethyl bromodifluoroacetate as a fluorine source. The Mitsunobu reaction as a key step was studied by 31P and 19F NMR for alkyl- and aryl-substituted α,α-difluoro-β-hydroxyesters and performed under optimized conditions giving the target compounds.