[CH3:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[N:9]=[N:10][NH:11][N:12]=2)=[CH:4][CH:3]=1.[C:13](O)([CH3:16])([CH3:15])[CH3:14].S(=O)(=O)(O)O>FC(F)(F)C(O)=O.C(OCC)(=O)C>[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[N:12]=[N:11][N:10]([C:13]([CH3:16])([CH3:15])[CH3:14])[N:9]=2)=[CH:6][CH:7]=1A solution of 5-(4-methylphenyl)-2H-tetrazole (W. G. Finnegan, R. A. Henry, R. Lofquist J. Am. Chem. Soc. 1958, 80, 3908.) (19.9 g, 0.12 mol), t-butanol (19.5 g, 0.26 mol) and concentrated sulfuric acid (5.84 g, 0.06 mol) in trifluoroacetic acid (122 mL) was stirred at room temperature (3 h) and then diluted with ethyl acetate (250 mL). The mixture was washed sequentially with water (2×50 mL), 10% aqueous sodium hydroxide until washings were basic, water (2×30 mL), and then dried over sodium sulfate (Na2SO4) and filtered. Following removal of the solvents in vacuo, the resultant oil was purified by HPLC on silica gel eluting with 20:1 mixture of hexanes-ethyl acetate to provide 17.5 g of 5-(4-methylphenyl)-2-(1,1-dimethylethyl)-2H-tetrazole as a clear oil, bp. 120°-122° C. (0.3 mm Hg).
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