Cl.[CH3:2][C:3]1[N+:4]([O-])=[C:5]([C:9]2[CH:14]=[CH:13][C:12]([C:15]([F:18])([F:17])[F:16])=[CH:11][CH:10]=2)[O:6][C:7]=1[CH3:8].O=P(Cl)(Cl)[Cl:22].O>C(#N)C>[Cl:22][CH2:2][C:3]1[N:4]=[C:5]([C:9]2[CH:14]=[CH:13][C:12]([C:15]([F:18])([F:17])[F:16])=[CH:11][CH:10]=2)[O:6][C:7]=1[CH3:8]The suspension of the title A compound, 4,5-dimethyl-2-(4-trifluoromethylphenyl)-oxazole 3-oxide hydrochloride (500 g, 1.70 mol) in 4.06 L of acetonitrile is stirred for 15 minutes at room temperature, then cooled to 10° C. 491 g (3.17 mol) of POCl3 are added at 15° C. over a period of 30 minutes. The suspension is stirred at room temperature for 16 hours, and the mixture is cooled to 10° C., and 6 L of water are added into the reaction mixture slowly (first 400 mL of water addition is very exothermic). The suspension is then stirred at room temperature for 6 hours further, and the solids are collected by filtration, washed with 2 L of water and dried to a constant weight at 50° C. (20 mbar) to afford 4-chloromethyl-5-methyl-2-[4-(trifluoromethyl)phenyl]-oxazole as a white solid (400 g, 85% yield): m.p. 97–98° C.
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