Water → 3-Imino-2-(1-methyl-3-phenylthioureido)isoindolin-1-one

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Reaction Steps

A solution of crude 2-cyanobenzoylchloride (2.2 g; 0.013 mole) in 20 ml of dimethoxyethane was added dropwise to a solution of 2-methyl-4-phenylthiosemicarbazide 0.35 g; 0.013 mole) and pyridine (1.1 g; 0.013 mole) in 35 ml of dimethoxyethane. The resulting red solution was allowed to stir at room temperature overnight. The reaction mixture was poured into a large volume of water to give a reddish gummy precipitate. The water was decanted and the gummy material dissolved in a small amount of ethyl acetate. Upon standing a solid crystallized from solution. Filtration gave 1 g of the desired product, mp: 165-167. The IR and NMR spectra were consistent with the cyclic tautomer structure, as illustrated in the foregoing reaction scheme. Under basic conditions, as in the exemplified synthesis procedure, existence of the tautomeric ortho-cyanobenzoyl compound is probably negligible. It is conceivable, however, that in some chemical environments the tautomeric form can be detected, or that reaction products derived from the tautomeric form will be produced when identification by preparation of chemical derivatives is attempted.

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