General procedure for the synthesis of 4-isopropoxybenzaldehyde from 2-iodopropane and p-hydroxybenzaldehyde: Referring to Example 3, to a 100 mL DMF solution containing 2 g (16.38 mmol) of p-hydroxybenzaldehyde was added sequentially 2.72 g (19.69 mmol) of K2CO3, 2.74 g (16.52 mmol) of KI, and 3.94 mL ( 39.38 mmol) 2-iodopropane and the reaction was carried out under argon protection. The reaction mixture was stirred at 80 °C overnight and subsequently concentrated. The concentrated residue was partitioned between CHCl3 and H2O to separate the organic and aqueous phases. The aqueous phase was further extracted with CHCl3 and after combining all the organic phases was dried and concentrated with MgSO4. The crude product was purified by silica gel column chromatography using a gradient polarity EtOAc/hexane mixed solvent as eluent, resulting in 2.08 g of oily 4-isopropoxybenzaldehyde in 77% yield. The structure of the product was confirmed by 1H-NMR (300 MHz, CDCl3, δTMS): 1.39 (d, J=6Hz, 6H), 4.67 (m, 1H), 6.96 (d, J=8.7Hz, 2H), 7.81 (d, J=8.7Hz, 2H), 9.87 (s, 1H).
