[Synthesis]
GENERAL STEPS: 4-Fluorobenzaldehyde (2.5 g, 20 mmol), diethylamine (5.12 g, 70 mmol), potassium carbonate (4.15 g), dimethylsulfoxide (25.0 mL), and Aliquat-336 (0.05 mL) were added to a 100 mL single-necked flask equipped with a stirrer and condenser. The reaction mixture was stirred at 95°C for 72 hours and subsequently cooled to room temperature. Upon addition of ice water, a yellow precipitate precipitated. The crude product was washed 2-3 times with cold water and recrystallized by ethanol to give N,N-diethyl-4-aminobenzaldehyde as a yellow solid. Yield: 92%. Elemental analysis calculated values (C11H15NO): C, 74.54; H, 8.53; N, 7.90; measured values: C, 74.67; H, 8.58; N, 7.85. 1H NMR (500 MHz, CDCl3, ppm) δ 9.71 (s, 1H), 7.72 (q, 2H), 6.69 (d, J = 8.8 Hz, 2H) , 3.46 (q, 4H), 1.24 (t, 6H). Step 2: Potassium metal (0.78 g, 20 mmol) was added to tert-butanol (11.3 mL, 120 mmol) in a 50 mL single-neck flask equipped with a condenser. After the potassium was fully reacted, 4-methylpyridine (0.975 mL, 10 mmol) and N,N-diethyl-4-aminobenzaldehyde (1.77 g, 10 mmol) were added. The mixture was heated with stirring at 80°C for 2 hours. After evaporation to remove the tert-butanol, 200 mL of dichloromethane was added and washed once with 200 mL of ice water. The aqueous phase was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate, the solvent was evaporated and the crude product was recrystallized from toluene. Yield: 86%.1H NMR (500 MHz, DMSO, ppm) δ 8.43 (d, J = 5.2 Hz, 2H), 7.42 (t, J = 8.8 Hz, 2H), 7.23 (d, J = 5.4 Hz, 2H), 7.04 (d, J = 8.7 Hz, 2H), 6.27-6.66 (m, 2H), 3.39 (m, 4H), 1.13 (m, 4H). 4H), 1.13 (t, 6H).13C NMR (500 MHz, CDCl3, ppm) δ 148.56-146.96 (m, py), 134.57 (s, py), 128.86 (s, benzene), 120.51-119.95 (d, benzene), 111.56 (s, CH=CH), 44.47 (s, CH2), 12.62 (d, J = 8.7 Hz, 2H), 6.27-6.66 (m, 2H), 3.39 (m, 2H), 3.39 (m, 6H). CH2), 12.62 (s, CH3). Calculated elemental analysis (C17H20N2, EI-MS: 253.3): C, 80.91; H, 7.99; N, 11.10; measured: C, 80.76; H, 7.91; N, 11.01. IR (KBr, cm-1): 3026 w, 2974 m, 1581 s, 1520 vs, 1408 m, 1355 m. 1329 w, 1272 m, 1185 m, 1158 m, 1074 w, 972 w, 818 m, 795 m, 518 w. Melting Point: 258°C. |