To a mixture of 2-[chloro(cyclohexyl)methyl]-3-methyl-1-benzofuran-5-carbonitrile (868 mg) synthesized above, methyl 4-aminobenzoate (546 mg), sodium iodide (902 mg) and N,N-dimethylformamide (10 mL) was added sodium carbonate (638 mg), and the mixture was stirred at 80° C. overnight. 1N Hydrochloric acid was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (30% ethyl acetate/hexane) to give a pale-brown solid. To a mixture of the obtained solid, tetrahydrofuran (20 mL), water (8 mL) and ethanol (10 mL) was added 1N lithium hydroxide aqueous solution (3.38 mL), and the mixture was stirred overnight with heating under reflux, and concentrated under reduced pressure. The residue was dissolved in water (40 mL), and 1N hydrochloric acid (3.50 mL) was added at 0° C. The resulting precipitate was collected by filtration to give the title object compound (621 mg, 53%) as a white solid.
