General procedure for the synthesis of furo[2,3-c]pyridin-7(6H)-one from ethyl chloroformate and 3-(3-furyl)acrylic acid: 5.0 g of 3-furyl-3-ylacetic acid and 4.3 g of triethylamine were dissolved in 50 mL of acetone, and 5.2 g of ethyl chloroformate was added slowly dropwise under cooling in an ice bath over a time period of 10 minutes, followed by continued stirring in an ice bath for 30 minutes. Next, an aqueous sodium azide solution prepared from 3.5 g of sodium azide dissolved in 15 mL of deionized water was added dropwise and stirred in an ice bath for another 1 hour. After the reaction was completed, 150 mL of ice water was added, the reaction mixture was extracted with benzene, the organic phase was dried with anhydrous magnesium sulfate, and concentrated under reduced pressure to about 20 mL, controlling the temperature of the liquid not to exceed 30 °C. The concentrate was slowly added dropwise to a mixture of 40 mL of diphenylmethane and 7 mL of tributylamine, and the mixture was heated to 220 °C over 1.5 h. Benzene was also removed by distillation to maintain the reaction temperature at 220 °C. After dropwise addition, the reaction solution was cooled and hexane was added to precipitate the product. The precipitated crystals were collected by filtration, washed with ethyl acetate and dried to afford 3.15 g (64% yield) of 6H-furo[2,3-c]pyridin-7-one. Product characterization data: 1H-NMR (DMSO-d6): δ 11.50 (br s, 1H), 8.07 (d, J = 1.9 Hz, 1H), 6.86 (d, J = 1.9 Hz, 1H), 6.50 (d, J = 6.9 Hz, 1H); Mass Spectrometry (m/e): 135 (M+, base peak).
![Furo[2,3-c]pyridin-7(6H)-one](/CAS/GIF/84400-98-6.gif)