Synthesis
Triethylamine (Et3N, 383 g, 3.78 mol) was added to a solution of N,O-dimethylhydroxylamine hydrochloride (138 g, 1.42 mol) in dichloromethane (DCM, 1.5 L) at room temperature (RT). 3-Fluorobenzoyl chloride (150 g, 946 mmol) was added dropwise to the stirred mixture at 0 °C and protected by nitrogen (N2). The reaction solution was stirred at the same temperature for 1 hour, followed by slow warming to room temperature and continued stirring for 10 hours. The reaction mixture was poured into water (~1 L) and extracted with ethyl acetate (EtOAc, 2 x 500 mL). The organic phases were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated. The residue was purified by fast column chromatography (eluent: petroleum ether, PE) to afford N-methyl-N-methoxy-3-fluorobenzamide (1-2) as a white solid (150 g, yield: 86.5%).1H NMR (400 MHz, CDCl3): δ 7.49-7.43 (1H, m), 7.41-7.32 (2H, m), 7.18 -7.10 (1H, m), 3.54 (3H, s), 3.34 (3H, s).
References
[1] Bioorganic and Medicinal Chemistry Letters, 2010, vol. 20, # 4, p. 1415 - 1419
[2] Patent: WO2016/145103, 2016, A1. Location in patent: Paragraph 0165
[3] Patent: US6174874, 2001, B1
[4] Patent: US2008/249095, 2008, A1. Location in patent: Page/Page column 44
