To a solution of 5-(2-chloropyridin-3-yl)-1H-pyrrole-3-carbaldehyde (207 mg) in tetrahydrofuran (20 mL) was added sodium hydride (60% in oil, 100 mg) at room temperature and the mixture was stirred for 10 min. 15-Crown-5 (552 mg) was added dropwise, and the mixture was stirred for 5 min. 6-Methylpyridine-3-sulfonyl chloride (250 mg) was added, and the mixture was further stirred for 1 hr. The reaction mixture was diluted with saturated aqueous sodium hydrogen carbonate solution, and extracted with ethyl acetate. The extract was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane-ethyl acetate=3:7→1:4) to give the title compound as a colorless oil (yield 90 mg, 25%).
