Acetic Anhydride → 4-formyl-3,8-dihydroxy-1,9-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepine-6-carboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

Dry 2-(3-methyl-6-formyl-2-carboxy-5-hydroxy-phenoxy)-3,5-dihydroxy-4-methyl-benzoic acid methyl ester (1 mmol) was added to acetic anhydride (15 ml) and the resulting mixture was refluxed for five hours at 145° C. The excess acetic anhydride was distilled out. The residue was added with crushed ice and then extracted with ethyl acetate. The combined extracts were washed successively with saturated NH4Cl solution and water, dried over anhydrous Na2SO4, concentrated and purified by column chromatography to afford 4-formyl-3,8-dihydroxy-1,9-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepine-6-carboxylic acid methyl ester (30%).

Provenance & Evidence