[Cl:1][CH:2]([Cl:6])[C:3](Cl)=[O:4].[CH3:7][CH:8]1[NH:13][C:12]2[CH:14]=[CH:15][CH:16]=[CH:17][C:11]=2[O:10][CH2:9]1.C(=O)([O-])[O-].[Na+].[Na+]>C1C=CC=CC=1.O.C(OCC)(=O)C>[Cl:1][CH:2]([Cl:6])[C:3]([N:13]1[C:12]2[CH:14]=[CH:15][CH:16]=[CH:17][C:11]=2[O:10][CH2:9][CH:8]1[CH3:7])=[O:4]5.3 ml (55 mmoles) of dichloroacetyl chloride are added dropwise, at a temperature of 20° to 25° C. and while stirring, to a suspension of 7.5 g (50 mmoles) of 2,3-dihydro-3-methyl-1,4-benzoxazine and 5.8 g (55 mmoles) of sodium carbonate in 120 ml of benzene. The reaction mixture is then stirred at the same temperature for 30 minutes and is then taken up in a mixture of water and ethyl acetate. The organic phase is washed with saturated sodium chloride solution, dried over sodium sulfate and evaporated. Crystallising the residue from diisopropyl ether gives 10.8 g of 4-dichloroacetyl-2,3-dihydro-3-methyl-1,4-benzoxazine, melting point 105°-107° C.
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