[H-].[Na+].[OH:3][C:4]1[CH:12]=[C:11]([OH:13])[CH:10]=[CH:9][C:5]=1[C:6]([OH:8])=[O:7].[CH2:14](Br)[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1.O>CN(C)C=O>[OH:3][C:4]1[CH:12]=[C:11]([OH:13])[CH:10]=[CH:9][C:5]=1[C:6]([O:8][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)=[O:7]To a solution of 3 g (0.1 mole) of sodium hydride (80% in oil) and 50 ml of dimethylformamide (DMF), there are slowly added 15.4 g (0.1 mole) of 2,4-dihydroxybenzoic acid dissolved in 50 ml of DMF. The mixture is stirred at ambient temperature until the cessation of gaseous emission. There are then added 13.1 ml (0.1 mole) of benzyl bromide and the mixture is stirred at ambient temperature until solubilization of the reaction medium. The reaction mixture is poured into water, and extracted with ethyl ether. The organic phase is decanted, washed with water, dried on magnesium sulfate and evaporated. The residue is purified by chromatography on a silica column by eluting with dichloromethane. 19.7 g (81% yield) of the expected ester having a melting point of 94°-95° C. are recovered.
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