Phosgene → 2,3-Dimethyl-8-{2-[(2-methylsulfanylethoxy)carbonylamino]-6-methylbenzylamino}imidazo[1,2-a]-pyridine hemifumarate

Participants

Reaction Conditions

Reaction Steps

A 20% strength solution of phosgene in toluene (2.8 ml) is diluted with anhydrous dichloromethane (15 ml) and cooled to 0° C. A solution of 2-methylsulfanylethanol (0.46 ml) and N-methylmorpholine (0.59 ml) in anhydrous dichloromethane (10 ml) is then added dropwise. The mixture is kept at 0° C. for a further 15 min, then warmed to RT and stirred for a further 30 min. A suspension of 8-(2-amino-6-methylbenzylamino)-2,3-dimethylimidazo[1,2-a]pyridine (1.0 g) and triethylamine (0.49 ml) in anhydrous dichloromethane (30 ml) is then added dropwise to the solution and it is additionally stirred at RT for 1 h. Aqueous sodium bicarbonate solution (70 ml) is then added and the mixture is stirred for a further 30 min. The organic phase is separated off and the aqueous phase is extracted with dichloromethane (3×50 ml). The combined organic phases are washed with water (50 ml), dried over magnesium sulfate and concentrated. The residue is taken up in a hot solution of fumaric acid (400 mg) in acetone (30 ml) and cooled to 4° C. The precipitate is filtered off and additionally precipitated from a little hot acetone by stirring. After drying in a high vacuum, 0.65 g (47%) of the title compound is isolated as a pale beige crystallizate. M.p. 174-176° C.

Provenance & Evidence