[CH3:1][N:2](C)[CH2:3][C:4]([C:6]1[CH:11]=[CH:10][C:9]([O:12][CH:13]([F:15])[F:14])=[CH:8][CH:7]=1)=[O:5].Cl[C:18]([O:20][CH3:21])=[O:19].C(OCC)C>C(Cl)Cl>[CH3:1][N:2]([CH2:3][C:4]([C:6]1[CH:11]=[CH:10][C:9]([O:12][CH:13]([F:14])[F:15])=[CH:8][CH:7]=1)=[O:5])[C:18]([O:20][CH3:21])=[O:19]To 16.8 g (73 mmole) of 2-dimethylamino-4'-difluoromethoxyacetophenone in 100 ml of methylene chloride cooled to 0° C. was added 7.6 g (81 mmole) of methyl chloroformate. After the addition was complete the reaction mixture was allowed to warm to 20° C. and stirred overnight. Concentration in vacuo, partitioning between diethyl ether and 1M aqueous hydrochloric acid, washing with brine, drying over anhydrous magnesium sulfate, and reconcentration in vacuo gave a crude oil. Chromatography of this oil on silica gel using diethyl ether in hexanes gave 12 g of 2-(N-methyl-N-(methoxycarbonyl)amino)-4'-difluoromethoxyacetophenone an oil, bp 150°-190° C. at 0.7 torr.
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