Yield:-

Reaction Conditions:

in diethyl ether;ethanol;

Steps:

25.a Step a

Step a 6-Fluoro-imidazo[1,2-a]pyridine-2-carboxylic acid ethyl ester To a solution of 2-amino-5-fluoropyridine (1.12 g) in diethyl ether (25 ml) was added ethyl bromopyruvate (1.25 ml). the mixture was stirred for 1 hour. The resultant solid was filtered off, suspended in ethanol and heated at reflux for 4 hours. The solvent was removed by evaporation and the residue partitioned between ethyl acetate (100 ml) and aqueous sodium bicarbonate solution (100 ml). The organic layer was separated, dried, (magnesium sulfate) and the solvent removed by evaporation. The residue was purified by flash chromatography (silica) eluding with ethyl acetate: hexane (3:1) to give the sub-title compound as a colourless solid (1.12 g). MS: ES⁺(M+H) 209 ¹H NMR (399.98 MHz, CDCl₃) δ 1.44 (3H, t), 4.46 (2H, q), 7.19 (1H, ddd), 7.68 (1H, dd), 8.07-8.09 (1H, m), 8.19 (1H, s).

References:

US2002/77337,2002,A1