2.4. Synthesis of 2-(Prop-2-yn-1-yloxy)benzaldehyde (3)

To a stirring solution of 3.0 mL of salicylaldehyde (1 eq., 30 mmol) in acetonitrile (80 mL), 10.37 g of potassium carbonate (2.5 eq., 75 mmol) were added. The mixture was stirred at room temperature and then 2.76 mL of propargyl bromide (1.1 eq., 31 mmol) were added, allowing it to react for 2 days. After that, the mixture was filtered, the liquid extracted three times with DCM/water (3 × 50 mL) and the organic residue was dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to obtain the brown pure solid 3 (3.21 g, 67% yield). The final product was analyzed through ¹H-NMR (400 MHz, Chloroform-d) δ 10.47 (s, 1H), 7.85 (dd, J = 7.7, 1.8 Hz, 1H), 7.56 (ddd, J = 8.3, 7.3, 1.8 Hz, 1H), 7.11 (dd, J = 8.5, 0.9 Hz, 1H), 7.08 (tt, J = 7.5, 0.9 Hz, 1H), 4.82 (d, J = 2.4 Hz, 2H), 2.58 (t, J = 2.4 Hz, 1H).