Pyridine-2-sulfonyl Chloride → ethyl 5-(3-methoxypropoxy)-7-[(pyridin-2-ylsulfonyl)amino]-1H-indole-2-carboxylate

Participants

Reaction Steps

To a mixture of ethyl 7-amino-5-(3-methoxypropoxy)-1H-indole-2-carboxylate (3.00 g) and pyridine (50 mL) was added pyridine-2-sulfonyl chloride (2.0 g) at 0° C., and the mixture was stirred at room temperature for 15 hr. The reaction mixture was concentrated, 1N hydrochloric acid and ethyl acetate were added to the residue, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed successively with water and saturated brine, dried (MgSO4), and concentrated. The obtained residue was subjected to silica gel column chromatography, and eluted with hexane-ethyl acetate (2:1-1:1, volume ratio) to give the title compound (4.02 g, yield 90%) as colorless crystals. The crystals were recrystallized from ethyl acetate-hexane to give colorless prism crystals. melting point 126-127° C.

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