Raney nickel (corresponding to 0.2 ml) was added to an ethanol (1 ml)/tetrahydrofuran (1 ml) solution of 2-(4-cyano-2-cyclopropyl-5-methyl-6-phenyl-1,3-benzoxazol-7-yl)-N,N-dimethylethanethioamide (I-314) (14.0 mg, 0.037 mmol), followed by stirring in an oil bath at 50° C. for 5 hours. The reaction liquid was filtered, the filtrate was concentrated, and the resulting residue was purified by preparative TLC (eluent, chloroform:methanol=10:1, v/v) to obtain the entitled compound (6.00 mg, 47%) as a white solid.
