General procedure for the synthesis of 3,5-dimethoxybenzonitrile from 3,5-dimethoxybenzenemethanol: In a 25 mL Schlenk tube equipped with a magnetic stirrer, CuCl (0.05 mmol, 5 mol%), DABCO (0.10 mmol, 10 mol%), and 4-HO-TEMPO (0.05 mmol, 5 mol%) were added in turn . Subsequently, a solution of 3,5-dimethoxybenzyl alcohol (1 mmol) and ammonia (25-28%, 3 mmol, 3.0 equiv) in acetonitrile (2 mL) was added. The reaction mixture was stirred at room temperature for 24 h under argon protection. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the mixture was diluted with water and extracted with ethyl acetate. The organic layers were combined and dried with anhydrous magnesium sulfate. Subsequently, the organic layer was concentrated under reduced pressure and the crude product was purified by column chromatography to afford the target product 3,5-dimethoxybenzonitrile.
