[Cl:1][C:2]1[CH:3]=[C:4]([C:8]2[NH:9][C:10](=O)[O:11][C:12]=2[CH2:13][CH2:14][C:15]([O:17][CH3:18])=[O:16])[CH:5]=[CH:6][CH:7]=1.P(Cl)(Cl)([Cl:22])=O.N1C=CC=CC=1.C(#N)C>O>[Cl:22][C:10]1[O:11][C:12]([CH2:13][CH2:14][C:15]([O:17][CH3:18])=[O:16])=[C:8]([C:4]2[CH:5]=[CH:6][CH:7]=[C:2]([Cl:1])[CH:3]=2)[N:9]=1To a solution of methyl 3-[4-(3-chlorophenyl)-2-oxo-2,3-dihydro-5-oxazolyl]propionate (3.0 g), phosphorus oxychloride (4 mL) was gradually added pyridine (0.86 mL) at room temperature and the mixture was stirred at 90° C. for 3 hrs. The reaction mixture was cooled and acetonitrile was added. The mixture was poured into water and the mixture was extracted with ethyl acetate. The organic layer was washed successively with water and saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography, and methyl 3-[2-chloro-4-(3-chlorophenyl)-5-oxazolyl]propionate (2.3 g, 72%) was obtained as an oil from a fraction eluted with ethyl acetate-hexane (4:1, volume ratio).
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