Ethanol → ethyl 3-(5-amino-3-tert-butyl-1H-pyrazol-1-yl)benzoate

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反応条件

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Sulfuric acid (concentrated, 15.7 mL, 295.7 mmol) was carefully added drop-wise to cold EtOH (600 mL) with stirring. To this, 3-hydrazinobenzoic acid (45 g, 295.7 mmol) and 4,4-dimethyl-3-oxopentanenitrile (40.7 g, 325.3 mmol) were added and then the mixture was heated at 90° C. for 48 h. Most of the solvent was evaporated at reduced pressure, and the residual mixture was diluted with ethyl acetate. The resulting mixture was washed with ice cold 2M NaOH followed by brine, and dried (Na2SO4). The solution was filtered through a bed of silica gel, washing with more ethyl acetate. Evaporation of ethyl acetate and treatment of the residue with dichloromethane/hexanes gave the product as an off-white crystalline solid (61 g, 71%). MS m/z 288.2 (M+H)+; calcd. mass 287. Retention time (LC-MS): 2.99 min. 1H-NMR (DMSO-d6): δ 8.16 (m 1H); 7.88 (m, 2H); 7.60 (t, 1H); 5.40 (s, 1H); 5.32 (s, 2H); 4.36 (q, 2H); 1.34 (t, 3H); 1.21 (s, 9H).

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