Formic Acid → 2-Chloro-5-fluoronicotinic acid

Participants

Reaction Conditions

Reaction Steps

To a round-bottomed flask under a N2 atmosphere were added degassed DMF (270 mL), Pd(OAc)2 (0.05 eq, 2.7 g, 11.9 mmol), PPh3 (0.1 eq, 6.2 g, 23.8 mmol), and degassed Et3N (6 eq, 200 mL, 1428.6 mmol). The mixture was stirred for 20 minutes, HCOOH (3 eq, 28 mL, 714.3 mmol) was then added. 5 minutes later, 2,6-dichloro-5-fluoronicotinic acid (50 g, 238.1 mmol) was added. The mixture was stirred at 50° C. The reaction was followed by analysis (1H NMR) of a worked-up aliquot. When all starting material was consumed (24 h), the mixture was cooled to 0° C. and water (500 mL) was added. After 20 minutes. The mixture was filtered through a pad of Celite that was rinsed with water. The mixture was basified to pH 9 with 30% aq. NaOH and washed with EtOAc (2×). HCl (12 N) was added slowly to pH 1 and the solution was saturated with NaCl. The mixture was extracted with EtOAc (3×). The combined organic extracts were washed with brine, dried (Na2SO4), and concentrated under reduced pressure to give 37 g (88%) of a beige solid used in the next step without further purification.

Provenance & Evidence