Cl.Cl[C:3]1[CH:8]=[CH:7][NH+:6]=[CH:5][CH:4]=1.[NH:9]1[C:13]2[CH:14]=[CH:15][CH:16]=[CH:17][C:12]=2[N:11]=[N:10]1.C(=O)([O-])[O-].[K+].[K+]>CN(C)C=O>[N:6]1[CH:7]=[CH:8][C:3]([N:10]2[N:11]=[C:12]3[CH:17]=[CH:16][CH:15]=[CH:14][C:13]3=[N:9]2)=[CH:4][CH:5]=1A mixture of 4-chloropyridinium hydrochloride (25.0 g, 166 mmol), benzotriazole (29.6 g, 249 mmol), potassium carbonate (69.1 g, 500 mmol), and dimethylformamide (DMF) (500 mL) was stirred and heated under argon at 130° C. for 3 days. After cooling, the solid was filtered off, and the solvent was evaporated under reduced pressure. The residue was treated with dichloromethane (200 mL), filtered and chromatographed using a column filled with silica gel (500 mL) and hexane/ethyl acetate (1:1) as an eluent. Fractions containing the desired product were combined, and the solvent was distilled off. The residue was triturated with ethanol, the solid was filtered off and dried in a vacuum oven to give 2-(pyridin-4-yl)-2H-benzo[d][1,2,3]triazole, 6.45 g, 20%). 1H NMR (400 MHz, CDCl3): δ 8.80 (m, 2H, pyridine), 8.26 (m, 2H, pyridine), 7.93 (m, 2H, benzotriazole), 7.46 (m, 2H, benzotriazole).
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