Hydrochloric Acid → 2-Amino-5H-s-triazolo[5,1-a]isoindole

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Reaction Steps

A mixture of 26.2 g of N-aminophthalimidine hydrochloride (0.142 mole) and 6.25 g of cyanamide (0.149 mole) in 270 ml of anhydrous toluene are refluxed for two hours then, after cooling, the resulting solid precipitate is recovered by filtration. Yield, 31 g of the hydrochloride of 1-(2-phthalimidinyl)- guanidine. M.p. 269-70°C. An amount of 7.6 g (0.033 mole) of this latter compound is added to a solution of 1.5 g of 80% sodium hydride (0.05 mole) in 90 ml of ethanol and the mixture is refluxed for five hours. The solvent is distilled off in vacuo and the solid residue is taken up with water and the pH of the mixture is brought to 7 by addition of acetic acid. Extraction with dichloromethane and evaporation of the organic phase yields 4.5 g (78%) of the title product. M.p. 193-4°C (from ethanol).

Provenance & Evidence