Add benzoic acid (977 mg, 8 mmol), dry DCM (20 mL) and catalytic amount of DMF in a 100 mL round-bottom flask. Cool the reaction mixture to 0°C and stir for 5 minutes. Add (COCl)2 (0.89 mL, 1.3 equiv.) dropwise to the reaction mixture and stir at room temperature for 4 hours. Concentrate the resulting mixture under reduced pressure to obtain acid chloride. Add catalytic amount of 4-dimethylaminopyridine, dry DCM (15 mL), MeNH2 (2 (M) in THF) (5.19 mL, 1.3 equiv.) and Et3N (1.56 mL, 1.4 equiv.) to the mixture in a 100 mL round-bottom flask. Cool the reaction mixture to 0°C. Add acid chloride (1.0 equiv.) dropwise at 0°C. Stir the reaction mixture at room temperature for 12 hours. Add water (40 mL) and seperate the organic layer. Extract the aqueous layer with DCM (3 x 30 mL). Wash the combined organic layer with saturated aqueous NaHCO3 (30 mL) solution followed by water (30 mL). Dry the organic layer over Na2SO4 and concentrated under reduced pressure. Purify the crude mass by silica gel column chromatography (20% ethyl acetate in hexane as eluent) to obtain N-methylbenzamide.
DOI: 10.1002/anie.202203539
