To a stirred suspension of 4-hydroxy-N,N,1,2-tetramethyl-1H-benzimidazole-6-carboxamide (50 mg, 0.21 mmol, WO 2004054984) in N,N-dimethylformamide (2 mL) was added sodium hydride (60% dispersion in mineral oil, 11 mg, 0.27 mmol) at room temperature. After stirring for 20 minutes, a solution of 4-chlorochromane (71 mg, 0.42 mmol, WO 2000078751) in N,N-dimethylformamide (1 mL) was added at room temperature. The reaction mixture was warmed to 70° C., and stirred for 6 hours at the same temperature. The reaction mixture was quenched with sodium hydrogencarbonate aqueous solution, and extracted with ethyl acetate (20 mL×2). The combined extracts were washed with water and brine, dried over magnesium sulfate, and concentrated in vacuum. The residue was purified by column chromatography on silica gel (ethyl acetate:methanol=10:1 as an eluent) to afford the title compound as a white solid (40 mg, 52%):
