Synthese Simple des Analogues Fluores, Phosphones ou Sulfones de L'Acide Aspartique

Two stable hemiaminals, N acylated by the p-nitrobenzoyl or Boc group and each substituted by the difluoroearboxylethylester moiety, were obtained in a single step from the corresponding ethylhemiacetal. The Boc compound, after acylation by trifluoroacetic anhydride followed by in situ reaction either with trimethylsilylated derivatives of cyanide or diethylphosphite, or with sodium sulfate, led to the protected carboxylic, phosphonic, and sulfonic alpha-aminoacids, respectively. Acid hydrolysis, preceded by acidolysis in the cases of the sulfonic and phosphonic compounds, led to the free aminoacids.