[CH2:1]([O:3][C:4]([C:6]1[N:7]=[N:8][N:9]([CH2:18][Si](C)(C)C)[C:10]=1[C:11]1[CH:16]=[CH:15][C:14]([Br:17])=[CH:13][CH:12]=1)=[O:5])[CH3:2].O.CCCC[N+](CCCC)(CCCC)CCCC.[F-]>C1COCC1>[CH2:1]([O:3][C:4]([C:6]1[N:7]=[N:8][N:9]([CH3:18])[C:10]=1[C:11]1[CH:16]=[CH:15][C:14]([Br:17])=[CH:13][CH:12]=1)=[O:5])[CH3:2]To a stirred solution of 5-(4-bromo-phenyl)-1-trimethylsilanylmethyl-1H-[1,2,3]triazole-4-carboxylic acid ethyl ester (6.5 g, 17.01 mmol) in THF (100 mL), was added water (0.61 ml, 34.03 mmol) and cooled to 0° C. Then TBAF (1M) solution in THF (20.41 mL, 20.41 mmol) was added to it and the mixture was stirred at 0° C. for 10 min. Volatiles were distilled off and crude mass was purified by normal silica gel column chromatography using EtOAc-hexane as eluting solvent to get 5-(4-bromo-phenyl)-1-methyl-1H-[1,2,3]triazole-4-carboxylic acid ethyl ester (4.7 g, 89.02%) as a white solid. LC-MS: 310 (M+H); 1H-NMR (400 MHz, DMSO-d6) δ ppm 1.14 (t, J=7.0 Hz, 3H), 3.91 (s, 3H), 4.18 (q, J=7.0 Hz, 2H), 7.51 (d, J=8.4 Hz, 2H), 7.75 (d, J=8.4 Hz, 2H). The regio-chemistry was confirmed by NOE study.
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