Cl.C(OCC)(=O)C.[CH2:8]([O:10][C:11](=[O:34])[C@H:12]([NH:26]C(OC(C)(C)C)=O)[CH2:13][CH2:14][C:15](=O)[C:16]1[CH:21]=[C:20]([F:22])[C:19]([F:23])=[C:18]([F:24])[CH:17]=1)[CH3:9]>C(OCC)(=O)C>[CH2:8]([O:10][C:11]([C@H:12]1[CH2:13][CH2:14][C:15]([C:16]2[CH:21]=[C:20]([F:22])[C:19]([F:23])=[C:18]([F:24])[CH:17]=2)=[N:26]1)=[O:34])[CH3:9]4 N hydrochloric acid/ethyl acetate (163 mL) was added to an ethyl acetate (30 mL) solution of (R)-2-t-butoxycarbonylamino-5-oxo-5-(3,4,5-trifluorophenyl) valeric acid ethyl ester (22.2 g), and stirring was continued for 3 hours at room temperature. The solvent was removed under a vacuum, and ethyl acetate and sodium bicarbonate aqueous solution were added to the residue, and the organic layer was partitioned. After washing the organic layer with brine, the resultant was dried over anhydrous magnesium sulfate. The solvent was removed under a vacuum, and the title compound (12.4 g) was obtained. The physical property values are as follows.
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