2.2.2. Synthesis of 3,5-Dimethyl-4-(4′-Methoxyphenyl)-1H-Pyrazole (P1)

Hydrazine hydrate (7.2 mmol, 0.36 mg) was added to a mixture of D1 (5.8 mmol, 1.2 g) in ethanol (10 mL) at room temperature. Then, the mixture was heated under reflux for 2 h. The reaction mixture was evaporated under reduced pressure and the residue was purified in ethanol to give a white solid (yield: 1.1 g, 91 %; ¹H NMR (400 MHz, CDCl₃) δ/ppm 7.22–7.19 (m, 2H), 6.98–6.95 (m, 2H), 3.85 (s, 3H), 2.30 (s, 6H). ¹³C NMR (100 MHz, CDCl₃): δ/ppm 158.0, 141.7, 130.4, 126.0, 118.0, 113.9, 55.2, 11.5. MS (MALDI+, dithranol) m/z: 203.1 [M + H]+. Analysis found C, 70.91; H, 6.94; N, 13.83. Calc for [C₁₂H₁₄N₂O]: C, 71.26; H, 6.98; N, 13.85%. FTIR ν/cm⁻¹ 3175 (N-H), 1613, 1577, 1530, 1247 (C-O-C)).