p-Toluenesulfonic acid → 1,2-Dibenzoylhexahydro-5-[2-(4-pyridinyl)ethyl]-1H-1,2,5-triazepine

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A mixture of 1,2-dibenzoyl-1H-1,2,5-triazepine (2.0 g), 4-vinylpyridine (1.42 g) and p-toluenesulfonic acid (1.21 g) in methanol (70 ml) was stirred and heated at 60° under a nitrogen atmosphere for 3 days. The foam, obtained after evaporation of the solvent, was mixed with dichloromethane and 10% sodium carbonate solution. The organic phase was washed with water until neutral washings were obtained and dried (Na2SO4). Evaporation of the solvent gave a foam, 2.25 g. The crude product was chromatographed on a column of silica gel; elution with ethanol-ethyl acetate-dichloromethane (1:4:5) giving a major component. A hydrochloride salt, 1/3 hydrate of the titled compound was formed in ethanol; wt. 1.2 g (38%), mp 247° dec.

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