[CH3:1][C:2]1[C:10]2[N:9]=[N:8][NH:7][C:6]=2[C:5]([C:11]([OH:13])=[O:12])=[CH:4][CH:3]=1.[C:14](=O)([O-])[O-].[Cs+].[Cs+].CI.[CH3:22][N:23]([CH3:26])C=O>>[CH3:14][O:13][C:11]([C:5]1[C:26]2[N:23]([CH3:22])[N:8]=[N:9][C:10]=2[C:2]([CH3:1])=[CH:3][CH:4]=1)=[O:12].[CH3:14][O:13][C:11]([C:5]1[C:6]2=[N:7][N:23]([CH3:26])[N:9]=[C:10]2[C:2]([CH3:1])=[CH:3][CH:4]=1)=[O:12]A solution of 4-methylbenzotriazole-7-carboxylic acid (0.1 g) in dimethyl formamide (20 ml) was treated with cesium carbonate (0.37 g) and methyl iodide (0.1 ml) stirred at 50° C. for 5 h. The reaction mixture was quenched with water (10 ml) and extracted with ethyl acetate (3×5 ml). The combined organic layers were dried over sodium sulfate and concentrated. Chromatographic purification (hexane/ethyl acetate 85:15) gave 1,4-dimethylbenzotriazole-7-carboxylic acid methyl ester (30 mg) and 2,4-dimethylbenzotriazole-7-carboxylic acid methyl ester (26 mg).
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