Citric Acid → 5-methyl-2-{7-[methyl(2-thienylsulfonyl)amino]-1H-indol-2-yl)-4,5-dihydro-1,3-thiazole-5-carboxylic acid

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Reaction Steps

A mixture of N-[2-(5-cyano-5-methyl-4,5-dihydro-1,3-thiazol-2-yl)-1H-indol-7-yl]-N-methylthiophene-2-sulfonamide (0.15 g), 2N aqueous sodium hydroxide solution (0.36 ml), tetrahydrofuran (3 ml) and ethanol (3 ml) was heated under reflux for 4 hr. 10% Aqueous citric acid solution was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4), and concentrated. The residue was subjected to silica gel column chromatography to give the title compound (0.11 g, yield 69%) as yellow crystals from a fraction eluted with tetrahydrofuran. melting point >232° C. (decomposition).

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