2-Piperidone → 5H,6H,7H,8H-imidazo[1,2-a]pyridine

Participants

Reaction Conditions

Reaction Steps

1.5 g of 2-piperidone was dissolved in 75 mL of mesitylene, 248 μL of titanium tetrachloride was added thereto, and heated at 140° C. A solution obtained by dissolving 4.02 g of aminoacetoaldehyde diethyl acetal to 45 mL of mesitylene was prepared, and was added dropwise to the previous mesitylene solution over 3 hours. The mixture was stirred at 140° C. for 70 hours, then cooled back to room temperature, and was extracted with a 2N aqueous solution of hydrochloric acid. The obtained aqueous layer was basified with a 5N aqueous solution of sodium hydroxide, and then was extracted with chloroform. The organic layer was washed with saturated brine, and then dried over anhydrous sodium sulfate. The insolubles were filtered, the filtrate was concentrated under reduced pressure, and then the purification was carried out by distillation under reduced pressure (3 mmHg, 120° C.), to obtain 375 mg of 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine [44-1] as a pale yellow oily product.

Provenance & Evidence