Acetic Acid → 2-Sulfanylidene-2,3-dihydro[1,2,4]triazino[1,6-a]indol-4(1H)-one

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Reaction Conditions

Reaction Steps

Into a 1 L beaker, 1-(3-benzoyl-thioureido)-1H-indole-2-carboxylic acid methyl ester (24.27 g, 0.07 mol) and a 2 M solution of sodium hydroxide in water (140 mL, 0.28 mol) were added. The mixture was heated at 85° C. for 75 minutes. The reaction was cooled to room temperature. Acetic acid (16.7 mL, 0.29 mol) was added at 0° C. and the mixture was stirred for 30 minutes. The solid was filtered and dried on filter overnight to afford a white solid, which was further dried under vacuum overnight. NMR indicated about 1:1 molar ratio of product to benzoic acid. Trituration and filtration from hot benzene removed the benzoic acid and afforded 2-thioxo-2,3-dihydro-1H-[1,2,4]triazino[1,6-a]indol-4-one (14.50 g, 96%), which was used in the next step without further purification. 1H-NMR (DMSO-d6) δ 10.29 (br s, 1H), 7.76 (d, J=8.4 Hz, 1H), 7.66 (d, J=8.1 Hz, 1H), 7.3 (br s, 1H), 7.27 (m, 1H), 7.12 (m, 1H), 6.88 (s, 1H).

Provenance & Evidence