Oxalyl chloride → Pyridine, 2,6-dichloro-3-(chloromethyl)-

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A solution of 2,6-dichloronicotinic acid (3.84 g), oxalyl chloride (2.0 g), and 1 drop of dimethylformamide in dichloromethane (25 ml), was stirred at room temperature for 18 hours. The solution was concentrated in vacuo to give 3.50 g of 2,6-dichloronicotinyl chloride which was added portionwise in dichloromethane (25 ml) to an ice cooled solution of 10,11-dihydro-5H-pyrrolo[2,1-c][1,4]-benzodiazepine (2.15 g) and diisopropylethylamine (2.03 g) in dichloromethane (50 ml). The mixture was stirred at room temperature for 18 hours and washed with saturated aqueous sodium bicarbonate. The organic phase was dried over anhydrous sodium sulfate and filtered through a short column of anhydrous sodium magnesium silicate. The combined organic phase was concentrated on a hot plate with the gradual addition of hexane until crystallization occurred. After cooling, the crystals were collected by filtration to yield 2.65 g of the title as an amorphous solid. m.p. 115-130° C. MS, m/z: 358.1 (M+H)+.

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