A mixture of 6,7-dimethoxy-3,4-dihydronaphthalene-2-carboxylic acid (476 mg, 2 mmol) and SOCl2 (1.5 mL, 20 mmol) in toluene (20 mL) was heated at 50° C. for 1 hour. The solvent was then removed under reduced pressure to give 6,7-dimethoxy-3,4-dihydronaphthalene-2-carbonyl chloride which was used directly in the next step without further purification. To a stirred solution of methyl 2-aminobenzoate (332 mg, 2.2 mmol) and Et3N (0.8 mL, 6 mmol) in anhydrous DCM (20 mL) was added 6,7-dimethoxy-3,4-dihydronaphthalene-2-carbonyl chloride in anhydrous DCM (2 mL) dropwise at 0° C. The resulting mixture was stirred at room temperature overnight. The reaction was quenched with water and extracted with DCM. The combined organic phase was dried over sodium sulfate, the solvent was removed under reduced pressure and the residue was purified by flash column, eluting with petroleum ether/ethyl acetate (10:1) to give methyl 2-(6,7-dimethoxy-1,2-dihydronaphthalene-3-carboxamido)benzoate (330 mg, 45%). LC-MS (ES-API); rt 9.27 min; m/z calculated for C21H21NO5 [M+Na]+ 390.1, found 390.1.
