(Step 4) A solution of 2-amino-5-chloronicotinamide (200 mg) and 1-(bromomethyl)-2-(cyclopentylsulfonyl)benzene obtained in Step 3 (530 mg) in DMF (5 ml) was stirred at 90° C. for 20 hr. The mixture was allowed to cool to room temperature, ethyl acetate was added, and the precipitated crystals were collected by filtration. The obtained crystals were dissolved in aqueous sodium hydrogen carbonate solution, and the solution was extracted with a mixed solvent of ethyl acetate-tetrahydrofuran. The organic layer was washed with saturated brine, dried over magnesium sulfate, and filtered. The solvent was evaporated under reduced pressure. The residue was purified by basic silica gel column chromatography (ethyl acetate:hexane=3:1). The obtained residue was dissolved in methanol, and 4N hydrogen chloride-ethyl acetate solution (0.5 ml) was added. The mixture was crystallized from methanol-ethyl acetate, and the precipitated crystals were collected by filtration, and recrystallized to give the title compound (70 mg).
