反应详情

To a solution of 2H-pyran-3,5(4H,6H)-dione, sodium salt (1.36 g, 10 mmol) in 50 mL of ethanol were added 1.5 mL of concentrated sulphuric acid and the reaction mixture was stirred at room temperature overnight. Most of the solution was evaporated under vacuum, the residue was neutralized with saturated sodium bicarbonate, product extracted with ethyl acetate (4×50 mL), organics combined dried with sodium sulfate, filtered and concentrated. Residue purified by column chromatography (silica gel. 200-300 mesh, eluting with ethyl acetate/petroleum ether=1/1) to afford 5-ethoxy-2H-pyran-3(6H)-one (641 mg, 45%) as yellow solid. LCMS: (M+H)+=143; 1H NMR (300 MHz, CDCl3): δ 5.44 (s, 1H), 4.25 (s, 2H), 4.06 (s, 2H), 3.98 (q, 2H, J=6.9 Hz), 1.38 (t, 3H, J=6.9 Hz).

1. customMost of the solution was evaporated under vacuum
2. extractionextracted with ethyl acetate (4×50 mL)
3. dry with materialorganics combined dried with sodium sulfate
4. filtrationfiltered
5. concentrationconcentrated
6. customResidue purified by column chromatography (silica gel. 200-300 mesh, eluting with ethyl acetate/petroleum ether=1/1)