Dimethyl Sulfate → methyl 7-methoxy-2',3',5',6'-tetrahydro-spiro[1,3-benzodioxole-2,4'-(4H)-pyran]-4-carboxylate

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Reaction Steps

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.

Provenance & Evidence