Dimethylformamide → N-methoxy-N-methyl-3-(trifluoromethoxy)benzamide

Beteiligte Stoffe

Reaktionsschritte

To a stirred solution of 3-(trifluoromethoxy)benzoic acid (20.0 g, 96.1 mmol) in dichloromethane (200 mL), cooled to 0° C. with a brine/ice bath, was added N,N-dimethylformamide (0.37 mL, 4.8 mmol) followed by oxalyl chloride (10.1 mL, 115 mmol). The resulting mixture was stirred 5 h at room temperature, until gas evolution stopped and a clear solution was obtained. The mixture was cooled to 0° C. with a brine/ice bath, N,O-Dimethylhydroxylamine (9.37 g, 96 mmol) was added at once, followed by dropwise addition of triethylamine (45.5 mL, 326 mmol) through a dropping funnel, while keeping the internal temperature below 10° C. The resulting suspension was diluted with dichloromethane (200 mL), stirred overnight at room temperature, poured into water (400 mL) and the aqueous layer was extracted with dichloromethane (2×150 mL). The organic layers were combined, washed with water (2×200 mL), dried (MgSO4), and concentrated in vacuo. The residue was purified over silica gel to afford N-methoxy-N-methyl-3-(trifluoromethoxy)benzamide as an oil [22.4 g, yield 80%; HPLC/MS:m/z=250 (M+H); log P(HCOOH)=2.41].

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