4-Fluorobenzoic Acid → 5Chloro-2-(4fluorophenyl)imidazo[4,5-b]pyridine

Participants

Reaction Steps

2,3-Diamino-6-chloropyridine (Davos-Bulk supplier, 2.25 g 15.6 mmol) and 4-fluorobenzoic acid (2.62 g 18.7 mmol) are treated with polyphosphoric acid (56.4 g) at 150° C. for 6 h. The reaction mixture is poured on ice-water/NH3conc. and extracted with ethyl acetate three times. The combined organic phases are dried over Na2SO4, filtered and evaporated to dryness to yield the crude product, which is purified by recrystallisation from ethyl acetate/tert.butyl methyl ether to yield the title compound (1.8 g 44%) as grey crystals.

Provenance & Evidence