Sulfuric Acid → 1-[4-(Imidazo[1,2-a]pyridin-2-yl)phenyl]ethan-1-one

Participants

Reaction Steps

A solution of methylmagnesium iodide (prepared from 3.6 g of magnesium and 22 g of methyl iodide) in 40 ml of ether is added dropwise to a mixture of 6.5 g of 4-(imidazo[1,2-a]pyridin-2-yl)benzonitrile and 50 ml of tetrahydrofuran with stirring on an ice bath. The mixture is heated under reflux for 3 hours, and the reaction mixture is cooled with salt and ice. 100 ml of 50% sulfuric acid is added dropwise to the reaction mixture, water is added, and the whole mixture is adjusted to pH 8 by addition of 20% sodium hydroxide. The crystalline precipitate is filtered off, washed with water and recrystallized from dimethylformamide to give 4.2 g of 2-(4-acetylphenyl)-imidazo[1,2-a]pyridine as colorless crystals melting at 209°-210°C. 2.2 g of the thus-obtained 2-(4-acetylphenyl)-imidazo[1,2-a]pyridine is heated with 0.45 g of sulfur and 10 ml of morpholine under reflux for 6 hours. The reaction mixture is cooled, and ethanol is added. The crystalline precipitate is filtered off and washed with ethanol to give 1.4 g of 4-(imidazo[1,2-a]pyridin-2-yl)phenylacetothiomorpholide as yellowish brown crystals melting at 204°-206°C.

Provenance & Evidence