To a solution of 5,5-dimethyl-5,6,7,8-tetrahydro-8-oxo-naphthalen-2-carboxylic acid (Compound E3, 386 mg, 1.77 mmol) in dimethylformamide (4 mL) was added 1-(3-dimethylaminopropyl)-3-ethylcarboimide hydrochloride (440 mg, 2.3 mmol) followed by dimethylamino pyridine (DMAP) (280 mg, 2.3 mmol). The mixture was stirred for 10 minutes, and benzyl 4-hydroxy benzoate (426 mg, 1.9 mmol) was added and stirred at ambient temperature for 16 hours. The mixture was diluted with ethyl acetate (100 mL) and washed with water (10 mL), brine (10 mL), dried and solvent distilled off. The title compound was obtained as a pale yellow solid after chromatographic purification.
