Triethylamine → 8-Amino-2,3,6-trimethylimidazo[1,2-a]pyridine

To a solution of 2,3-diamino-5-methylpyridine (2.0 g, 16 mmol) in ethanol (100 ml) was added 3-bromo-2-butanon (2.4 g, 16 mmol). The reaction mixture was refluxed for 16 h. An additional amount of 3-bromo-2-butanon (1.0 g 6.7 mmol) and triethylamine (1.0 g, 9.9 mmol) were added and the mixture was refluxed for 2 h. The ethanol was evaporated under reduced pressure and the residue was treated with methylene chloride and a solution of bicarbonate. The organic layer was separated, dried over sodium sulfate and evaporated under reduced pressure. The oily residue was purified by column chromatography on silica gel, using methanol:methylene chloride (1:20) as eluent to give the desired product (1.05 g, 37%).