反应详情

Methyl 4-methyl-2,6-dihydroxybenzoate (14.0 grams, 76.8 mmoles) was dissolved in anhydrous dichloromethane (250 mL) and acetic anhydride (21 mL, 223 mmoles) and anhydrous pyridine (18 mL, 223 mmoles) were added carefully. The solution was refluxed under dry nitrogen for 30 hours, then cooled to room temperature. The solution was washed twice with 1 M aqueous hydrochloric acid (200 mL portions) and then with saturated aqueous sodium chloride (200 mL). The dichloromethane solution was dried over anhydrous magnesium sulfate, filtered, and evaporated to an off-white solid. This crude product was flash chromatographed on silica gel (250 grams) using hexanes:ethyl acetate (70:30 [v/v]) as the eluting solvent. Fractions containing the major product (Rf =0.3) were pooled and evaporated to dryness to afford 19.0 grams (98% yield) of a white solid of methyl 4-methyl-2,6-diacetoxybenzoate (m.p. 70-71° C., open capillary, uncorrected).

1. temperatureThe solution was refluxed under dry nitrogen for 30 hours
2. washThe solution was washed twice with 1 M aqueous hydrochloric acid (200 mL portions)
3. dry with materialThe dichloromethane solution was dried over anhydrous magnesium sulfate
4. filtrationfiltered
5. customevaporated to an off-white solid
6. customchromatographed on silica gel (250 grams)
7. additionFractions containing the major product (Rf =0.3)
8. customevaporated to dryness