反应详情

3.8 g of 4-(3,4-dihydroquinoxalin-1(2H)-yl)benzoic acid and 70 ml of methanol are introduced into a 250 ml round-bottomed flask equipped with a magnetic stirrer. 4.4 ml of 97% sulfuric acid are added dropwise and the reaction medium is stirred at ambient temperature for 18 h. The methanol is partially evaporated. The remaining solution is poured onto a water-plus-ice mixture, neutralized by slow addition of sodium hydrogencarbonate and extracted 3 times with ethyl acetate. The organic phases are combined, washed with water and with a saturated sodium chloride solution, dried over sodium sulfate and concentrated under reduced pressure. The residue is chromatographed on silica gel eluted with a gradient of ethyl acetate from 10% to 20% in heptane. 2.8 g of methyl 4-(3,4-dihydroquinoxalin-1(2H)-yl)benzoate are obtained.

1. customequipped with a magnetic stirrer
2. customThe methanol is partially evaporated
3. additionThe remaining solution is poured onto a water-plus-ice mixture
4. additionneutralized by slow addition of sodium hydrogencarbonate
5. extractionextracted 3 times with ethyl acetate
6. washwashed with water and with a saturated sodium chloride solution
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated under reduced pressure
9. customThe residue is chromatographed on silica gel
10. washeluted with a gradient of ethyl acetate from 10% to 20% in heptane