| 摘要 |
The present invention relates to a process for preparing derivatives of 3-amino-4-(2,4,5-trifluorophenyl)-butanoic acid of the general formula I, which are particularly useful as advanced intermediates of some dipeptidyl peptidase-4 (DPP-4) inhibitors. In the general formula 1 Pg represents a commonly used protecting group and R denotes NR1R2, wherein R1 and R2 are the same or different substituents, which can be hydrogen, a substituted or non unsubstituted alkyl group containing 1 to 6 carbon atoms and optionally R1 forms along with R2 a substituted or unsubstituted 4,5,6-membered heterocycle containing at least one nitrogen atom, especially a piperazine derivative. The reaction is carried out using a condensation agent of the general formula 3, in which X denotes a halide anion, in the presence of a polar organic solvent. |
