Citric Acid → HCID 57476348, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of ethyl (2-{7-[methyl(pyridin-3-ylsulfonyl)amino]-1H-indol-2-yl}-4,5-dihydro-1,3-thiazol-5-yl)acetate (330 mg), 1N aqueous sodium hydroxide solution (5 mL), tetrahydrofuran (5 mL) and ethanol (5 mL) was stirred at 50° C. for 30 min. The reaction mixture was acidified with aqueous citric acid solution, and extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4), and concentrated to give pale-yellow crystals. A mixture of the obtained crystals, 1H-1,2,3-benzotriazol-1-ol-ammonia complex (1.10 g), N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimide hydrochloride (1.38 g) and N,N-dimethylformamide (10 mL) was stirred at room temperature for 2.5 days. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed successively with saturated aqueous sodium hydrogencarbonate and saturated brine, dried (MgSO4), and concentrated. The residue was subjected to silica gel column chromatography, and eluted with ethyl acetate-methanol (100:0-85:15, volume ratio) to give the title compound (130 mg, yield 42%) as colorless crystals. The crystals were recrystallized from ethyl acetate-hexane to give colorless prism crystals. melting point 185-186° C.

Provenance & Evidence