反应详情

Ethyl glycolate (35.5 mL, 375 mmol) is slowly added (over 20 minutes) to a slurry of NaOH (15.8 g, 394 mmol) in 1,2-dimethoxyethane (400 mL) under N2 with the flask being in an ice bath. The mixture is allowed to warm to rt, is stirred for 30 min, and ethyl 2-chloronicotinate (27.84 g, 150 mmol) in 1,2-dimethoxyethane (50 mL) is added over 10 minutes. The reaction is warmed to 65° C. for 15 h in an oil bath. The mixture is concentrated to dryness, the residue is dissolved in H2O (500 mL), washed with hexane (500 mL), acidified to pH 3 with 5% HCl, and extracted with CHCl3 (4×400 mL). The combined organic layer is dried over MgSO4, filtered, and concentrated to a yellow solid. The solid is suspended in ether (200 mL) and heated on a steam bath until concentrated to a volume of 40 mL. The material is allowed to crystallize overnight, then filtered to afford ethyl 3-hydroxyfuro[2,3-b]pyridine-2-carboxylate (C40) as a pale orange solid (41% yield). Additional material is obtained by concentrating the filtrate. Recrystallization in ether a second time afforded (C40) as a pale yellow solid (7.3% yield). MS (EI) for C10H9NO4, m/z: 207 (M)+.

1. custombeing in an ice bath
2. temperatureThe reaction is warmed to 65° C. for 15 h in an oil bath
3. concentrationThe mixture is concentrated to dryness
4. dissolutionthe residue is dissolved in H2O (500 mL)
5. washwashed with hexane (500 mL)
6. extractionextracted with CHCl3 (4×400 mL)
7. dry with materialThe combined organic layer is dried over MgSO4
8. filtrationfiltered
9. concentrationconcentrated to a yellow solid
10. temperatureheated on a steam bath
11. concentrationuntil concentrated to a volume of 40 mL
12. customto crystallize overnight
13. filtrationfiltered