反应详情

Ethyl 2-ethoxycarbonylimidazo[1,2-a]pyridine-8-carboxylate (3.8 g, 14.5 m mol) was dissolved in conc. sulfuric acid (10 ml), and to the solution was slowly added 70% nitric acid (1.5 ml) at 10° C. The mixture was stirred at room temperature for 30 minutes, poured into ice water and adjusted to pH 7 by adding 20% sodium hydroxide. The precipitated crystals were filtered to obtain ethyl 2-ethoxycarbonyl-3-nitro-imidazo[1,2-a]pyridine-8-carboxylate (2.4 g, yield 53.8%) as crystals of m.p. 139°-140° C. A solution of the crystals in conc. hydrochloric acid (35 ml) was refluxed for 1.5 hours and cooled to room temperature. The precipitated crystals were collected by filtration and dried to give the object compound (1.2 g, yield 74.3%) of m.p.>300° C.

1. customat 10° C
2. filtrationThe precipitated crystals were filtered