2,6-Dichlorobenzoyl chloride → 2,6-dichloro-N-(2,6-dichlorobenzoyl)-N-(3,5-difluoropyridin-4-yl)-benzamide

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Reaction Steps

2,6-Dichlorobenzoyl chloride (13.7 mL, 95.6 mmol) was added dropwise, over 10 minutes, to a solution of 3,5-difluoropyridin-4-ylamine (10.37 g, 79.7 mmol) in pyridine (160 mL) at a temperature of between 3 and 5° C., under argon. The reaction mixture was allowed to warm to room temperature over 1 hour and then stirred at room temperature for 2 hours. The volatiles were removed under reduced pressure and the resultant residue was treated with HCl (1N, 120 mL). The resultant suspension was stirred at room temperature for 45 minutes and the precipitate was collected by filtration, washing with water. A mixture of 2,6-dichloro-N-(3,5-difluoropyridin-4-yl)-benzamide and of 2,6-dichloro-N-(2,6-dichlorobenzoyl)-N-(3,5-difluoropyridin-4-yl)-benzamide (22.0 g) was obtained. A suspension of this mixture (22.0 g) in 1N NaOH (200 mL) and MeOH (200 mL) was heated at 65° C. for 7 hours then slowly cooled to room temperature. The pH of the mixture was adjusted to 4-5 by dropwise addition of 12N HCl, controlling the exotherm by the use of an ice-bath. The residue was left standing at room temperature for 18 hours and then the resultant solid was collected by filtration, washing with water, to afford the title compound as an off-white solid (14.65 g, 61% yield over two steps). LCMS (Method D): RT=2.93 min, m/z: 303 [M+H+].

Provenance & Evidence