[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[NH:9][C:10](=[O:13])[O:11][CH:12]=2)=[CH:4][CH:3]=1.S(=O)(=O)(O)O.[C:19]([O:23][CH3:24])(=[O:22])[CH:20]=[CH2:21].CO>C(#N)C.O>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[NH:9][C:10](=[O:13])[O:11][C:12]=2[CH:20]([CH3:21])[C:19]([O:23][CH3:24])=[O:22])=[CH:6][CH:7]=14-(4-chlorophenyl)-2-oxo-4-oxazoline (5.00 g) was suspended in acetonitrile (15 ml) in a reaction vessel, and the gas in the reaction vessel was substituted for nitrogen gas. The obtained suspension was cooled and conc. sulfuric acid (7.53 g) was added dropwise at 2-10° C. Then methyl acrylate (4.41 g) was added dropwise at 2-3° C. The obtained mixture was stirred at 20-30° C. for 1.5 h and methanol (15 ml) was added dropwise at 22-25° C. After cooling, water was added dropwise at 5-8° C. The precipitated crystals were collected by filtration, washed with water (25 ml), 1% aqueous sodium hydrogencarbonate (25 ml), water (25 ml) and diisopropyl ether (25 ml), and dried under reduced pressure at 40° C. for 7 h to give the title compound (5.72 g, yield 79.4%) as pale-red white crystals.
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