Dibromomethane → Methyl 3,4-methylenedioxy-5-methoxybenzoate

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Reaction Conditions

Reaction Steps

Cesium fluoride (26.5 g, 174 mmol) was added quickly to a stirred solution of diol 4 (7.7 g, 39 mmol) in DMF (80 ml) at rt under Ar. After stirring for 1 h, dibromomethane (5.4 ml, 78 mmol) was added dropwise at rt and the mixture heated to 110° C. for 12 h. Upon cooling to rt, ether (300 ml) was added and the mixture washed with cold water (3×50 ml). The combined aqueous phase was then extracted with ether (2×100 ml), dried and concentrated in vacuo. The resultant crude residue was absorbed onto silica gel (gravity) and purified via silica gel chromatography (gravity, 1:5; EtOAc in n-hexane), affording methylenedioxy derivative 5 (8.1 g, 99%) as a colorless powder; m.p. 89–91° C. (mp 89–91° C., Pettit and Singh, 1987); 1H-NMR (300 MHz):3.89 (3H, s, —OCH3), 3.94 (3H, s, —OCH3), 6.05 (2H, s, —OCH2O—), 7.21 (1H, d,J=1.8 Hz, ArH), 7.33 (I H, d, J=1.8 Hz, ArH).

Provenance & Evidence