Water → 5-Amino-2-fluoroisonicotinic acid

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반응 단계

A suspension of 36.6 g (140 mM) of 5-[N-(tert-butoxycarbonyl) amino]-2-fluoropyridine-4-carboxylic acid hydrated with 0.3 equivalents of water in 280 mL of dichloromethane was cooled in an ice bath then treated dropwise over 15 minutes with 140 mL of trifluoroacetic acid. The bath was removed, and the resultant mixture was stirred at room temperature for 14 hours, then concentrated. The yellow-orange solids were triturated in 125 mL of warm 1:1 diethyl ether:dichloromethane. After cooling, the yellow solids were collected, washed with 100 mL of the diethyl ether:dichloromethane mixture, and dried to afford 19.3 g of product. Processing of the filtrate afforded 1.7 g of a second crop. Total yield=21 g (94%). Recrystallization of a small sample from ethyl acetate provided product of mp 259° C. (dec). 1H NMR [(CD3)2SO]: δ8.86 (m, 3H), 7.81 (d, JH-F=1.1 Hz, 1H), 7.20 (d, JH-F=2.3 Hz, 1H).

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