反应详情

A solution of 8-(2-nitro-6-methylbenzylamino)-3-chloro-2-methylimidazo[1,2-a]pyridine (2.0 g, 6 mmol) in methanol (175 ml) and dioxane (175 ml) is treated with platinum-on-carbon catalyst (5% strength) and hydrogenated at RT under atmospheric pressure for 2 h. After 2 h, 2N hydrochloric acid (5 ml) is added and the mixture is hydrogenated under the same conditions again for 1 h. The catalyst is then filtered off, the filtrate is adjusted to pH 8.5 using 2N sodium hydroxide solution and the solvent is distilled off on a rotary evaporator. The residue is dissolved in boiling ethyl acetate (400 ml). After cooling to RT, diisopropyl ether (250 ml) is added and, to complete crystallization, the mixture is stirred at 4° C. for 30 min. The precipitate is then filtered off with suction, washed with diisopropyl ether and dried in vacuo. The title compound (1.66 g, 92%) is isolated as a beige solid. M.p. 243-246° C.

1. waitthe mixture is hydrogenated under the same conditions again for 1 h
2. filtrationThe catalyst is then filtered off
3. distillationthe solvent is distilled off on a rotary evaporator
4. dissolutionThe residue is dissolved
5. additiondiisopropyl ether (250 ml) is added
6. customcrystallization
7. filtrationThe precipitate is then filtered off with suction
8. washwashed with diisopropyl ether
9. customdried in vacuo