Cl.[CH3:2][O:3][C:4]1[CH:9]=[CH:8][C:7]([NH:10][NH2:11])=[CH:6][CH:5]=1.C(N(CC)CC)C.[C:19]([CH2:25][C:26]#[N:27])(=O)[C:20]([CH3:23])([CH3:22])[CH3:21]>C1(C)C=CC=CC=1>[C:20]([C:19]1[CH:25]=[C:26]([NH2:27])[N:10]([C:7]2[CH:8]=[CH:9][C:4]([O:3][CH3:2])=[CH:5][CH:6]=2)[N:11]=1)([CH3:23])([CH3:22])[CH3:21]Solid 4-methoxyphenylhydrazine hydrochloride (25.3 g) was suspended in toluene (100 mL) and treated with triethylamine (20.2 g). The mixture was stirred at RT for 30 min and treated with pivaloylacetonitrile (18 g). The reaction was heated to reflux and stirred overnight. The hot mixture was filtered, the solids washed with hexane and dried in vacuo to afford 3-tert-butyl-1-(4-methoxyphenyl)-1H-pyrazol-5-amine (25 g, 70%). 1H NMR (DMSO-d6): δ 7.5 (d, 2H), 7.0 (d, 1H), 6.4 (s, 11H), 6.1 (s, 2H), 3.9 (s, 34H), 1.3 (s, 9H).
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