4-Ethynyl-benzoic acid methyl ester

3-(4-(methoxycarbonyl)phenyl)propanoic acid (204 mg, 1.0 mmol) and N,N,N',N'-tetramethylethylenediamine (2.0 mmol) were added to a vacuum-dried reaction flask and reacted in dimethyl sulfoxide (3.0 mL) at 65 °C for 12 hours. The reaction progress was monitored by TLC. After the reactants had completely reacted, the reaction was quenched with saturated ammonium chloride aqueous solution. The mixture was diluted with ethyl acetate and washed with saturated sodium chloride (20 mL x 2). The organic layer was separated and dried with anhydrous magnesium sulfate. The reaction mixture was filtered to remove sodium sulfate solids. The obtained organic layer was concentrated under vacuum to remove the solvent, yielding a crude product. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate = 40/1) to obtain the target product, 4-ETHYNYL-BENZOIC ACID METHYL ESTER.