Hydrochloric Acid → 7-acetyl-5H-[1]benzopyrano[2,3-b]pyridine

Participants

Reaction Steps

30.5 g of acetyl chloride is placed in a four-necked flask fitted with a stirrer. A mixture of 49 g of crushed aluminum chloride and 20 g of crushed 5H-[1]benzopyrano[2,3-b]pyridine is added in small portions over a period of 30 minutes, keeping the temperature at 10°-20°C by cooling with ice water. After the addition the temperature is raised to 50°-60°C over 1 hour. Violent release of hydrogen chloride takes place. The contents gradually become viscous, and stirring becomes difficult. The contents are allowed to stand at 80°-85°C for 2 hours without stirring. The contents are broken to pieces and thrown into 1 liter of ice water. The crystalline precipitate is filtered off, washed with water, dried, and then recrystallized from ethyl acetate to give 18.5 g of 7-acetyl-5H-[1]benzopyrano[2,3-b]pyridine melting at 142°-144°C.

Provenance & Evidence