反应详情

A suspension of the crude 7-methoxy-2′,3′,5′,6′-tetrahydro-spiro[1,3-benzodioxole-2,4′-(4H)-pyran]-4-carboxylic acid (2.17 g, 8.15 mmol), KHCO3 (2.58 g, 26.0 mmol) and dimethyl sulphate (1.58 mL, 16.7 mmol) in acetone (62 mL) was stirred at room temperature for two days before it was evaporated to dryness under reduced pressure. Ethyl acetate (100 mL) was added. The organic phase was washed with 0.5 M aqueous NaOH (6×30 mL) and evaporated to dryness under reduced pressure. The crude product was redissolved in dichloromethane (75 mL), dried over MgSO4 and evaporated to dryness under reduced pressure. Standard silica gel column chromatography afforded methyl 7-methoxy-2′,3′,5′,6′-tetrahydro-spiro[1,3-benzodioxole-2,4′-(4H)-pyran]-4-carboxylate (1.87 g, 79%). 13C NMR (CDCl3) δ 164.9, 149.1, 147.2, 135.2, 124.0, 117.5, 107.1, 106.5, 65.2, 56.4, 51.8, 35.9.

1. customwas evaporated to dryness under reduced pressure
2. additionEthyl acetate (100 mL) was added
3. washThe organic phase was washed with 0.5 M aqueous NaOH (6×30 mL)
4. customevaporated to dryness under reduced pressure
5. dissolutionThe crude product was redissolved in dichloromethane (75 mL)
6. dry with materialdried over MgSO4
7. customevaporated to dryness under reduced pressure