N-tert-butoxycarbonylamino-O-(2,5-difluorobenzyl)-D-serine

[(R)-1-{[5-(4-Chloro-phenyl)-3,3-dimethyl-1,1-dioxo-2,3-dihydro-1H-1λ6-isothiazol-4-ylmethyl]-ethyl-carbamoyl}-2-(2,5-difluoro-benzyloxy)-ethyl]-carbamic acid tert-butyl ester