反应详情

Compounds of this invention can be prepared as illustrated by the exemplary reaction in Scheme 2. Coupling of a 2,5-dihalopyridine, such as 5-bromo-2-chloropyridine, with a substituted phenylboronic acid, such as 4-methoxyphenylboronic acid, in the presence of a palladium catalyst, such as tetrakis(triphenylphosphine)palladium, produced 2-chloro-5-(4-methoxyphenyl)pyridine. Reaction of 2-chloro-5-(4-methoxyphenyl)pyridine with hydrazine produced 2-hydrazinyl-5-(4-methoxyphenyl)pyridine. Reaction of 2-hydrazinyl-5-(4-methoxyphenyl)pyridine with a substituted benzoic acid, such as 4-chloro-2-methoxybenzoic acid, in the presence of coupling agents, such as BOP (benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate) and NMM (N-methylmorpholine), produced 4-chloro-2-methoxy-N-(5-(4-methoxyphenyl)pyridin-2-yl)-benzohydrazide. Treatment of 4-chloro-2-methoxy-N-(5-(4-methoxyphenyl)pyridin-2-yl)-benzohydrazide with phosphorus oxychloride produced the cyclized product 3-(4-chloro-2-methoxyphenyl)-6-(4-methoxyphenyl)-[1,2,4]triazolo[4,3-a]pyridine, which can be converted into a salt by treatment with HCl in ethyl acetate.