4-Formylphenylboronic acid (0.5 mmol), phenylacetylene (0.6 mmol), dichloromethane (2 mL), Catalyst 3 (2 mol%), silver oxide (Ag2O, 1.0 mmol), and potassium acetate (KOAc, 1.0 mmol) were sequentially added to the Schlenk tube. The reaction mixture was stirred at 35 °C for 24 h under argon protection. Upon completion of the reaction, excess dichloromethane was removed by rotary evaporation and the residue was purified directly by silica gel column chromatography (eluent was petroleum ether or mixed petroleum ether/ethyl acetate solvent) to afford the target product, 4-(phenylalkynyl)benzaldehyde (32d, Table 1, entry 11) (99 mg, 96% yield). The product was a white solid, melting point: 98-100 °C; 1H NMR (400 MHz, CDCl3) δ 9.99 (s, 1H), 7.84 (d, J = 7.8 Hz, 2H), 7.66 (d, J = 8.0 Hz, 2H), 7.56 (dd, J = 3.4, 2.9 Hz, 2H), 7.37 (s, 3H); 13C NMR ( 100 MHz, CDCl3) δ 191.6, 135.3, 132.0, 131.7, 129.6, 128.9, 128.43, 128.41, 122.4, 93.5, 88.5.
