反应详情

A solution of 3.90 g of ethyl 1,2-dihydro-2-oxoquinoxaline-3-carboxylate in 25 ml of N,N-dimethylformamide was added dropwise to a suspension of 0.79 g of 60% sodium hydride/oil in 10 ml of N,N-dimethylformamide at room temperature over 30 minutes. After stirring at room temperature for 30 minutes, 3.36 g of benzyl bromide was added dropwise over 10 minutes, followed by stirring at room temperature overnight. The reaction mixture was concentrated under reduced pressure. The residue, after addition of ethyl acetate, was washed with water, 1 N hydrochloric acid, a saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate. After removal of the drying agent by filtration, the filtrate was concentrated under reduced pressure. The residue was purified by chromatography (silica gel; Wakogel C200 (manufactured by Wako Pure Chemicals), developing solvent; hexane−ethyl acetate=10:1−2:1) and recrystallized from ethyl acetate−hexane to give 3.77 g of ethyl 1-benzyl-1,2-dihydro-2-oxoquinoxaline-3-carboxylate.

1. stirringby stirring at room temperature overnight
2. concentrationThe reaction mixture was concentrated under reduced pressure
3. additionThe residue, after addition of ethyl acetate
4. washwas washed with water, 1 N hydrochloric acid
5. dry with materiala saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate
6. customAfter removal of the drying agent
7. filtrationby filtration
8. concentrationthe filtrate was concentrated under reduced pressure
9. customThe residue was purified by chromatography (silica gel; Wakogel C200 (manufactured by Wako Pure Chemicals), developing solvent; hexane−ethyl acetate=10:1−2:1)
10. customrecrystallized from ethyl acetate−hexane