Synthesis
General procedure for the synthesis of methyl benzo[d][1,3]meso-dioxole-4-carboxylate from methyl 2,3-dihydroxybenzoate and dibromomethane: 6.0 g (0.036 mol) of methyl 2,3-dihydroxybenzoate and cesium carbonate (0.54 mol) were dissolved in 50 mL of N,N-dimethylformamide (DMF). 11.5 mL of dibromomethane (0.54 mol) was added slowly and dropwise at room temperature. After the dropwise addition, the temperature of the reaction system was raised to 110 °C and the reaction was maintained at this temperature for 3 hours. After completion of the reaction, the reaction was cooled to room temperature, stopped and filtered. Equal volumes of water and ethyl acetate were added to the filtrate for liquid-liquid separation. The aqueous phase was extracted twice with ethyl acetate, and all organic phases were combined and washed with water and saturated saline in that order. The organic phase was dried with anhydrous sodium sulfate for 8 minutes. The desiccant was removed by filtration, the solvent was removed by evaporation under reduced pressure and the residue was purified by silica gel column chromatography. Petroleum ether: ethyl acetate (6:1, v/v) was used as eluent to collect the target component, and 5.2 g of white solid product was obtained after evaporation under reduced pressure in 81.2% yield.
References
[1] Patent: CN103804341, 2018, B. Location in patent: Paragraph 0064; 0068; 0069
[2] Journal of Medicinal Chemistry, 2004, vol. 47, # 4, p. 871 - 887
[3] Patent: US2004/34046, 2004, A1
[4] Patent: WO2004/4732, 2004, A1. Location in patent: Page/Page column 65-66
[5] Patent: WO2005/34939, 2005, A1. Location in patent: Page/Page column 76
