N-Methylation Of Amines With Methanol Catalyzed By A Cp~*Ir Complex Bearing A 2,2'-bibenzimidazole Ligand

Amine methylation reaction is a kind of important chemical reaction,which is widely used in the synthesis of key intermediates such as natural products,fine chemicals and drugs.Conventional synthesis methods commonly react with high toxicity methyl iodide with amines.This method uses highly toxic halohydrocarbons and produces a large amount of waste salts that are harmful to the environment.Based on hydrogen auto-transfer mechanism,researchers use transition metal catalysts to catalyze the methylation of methanol as a methylating agent with amines.Although there has been great progress in the study of the reaction of methanol and amine catalyzed by transition metal,this series of reaction conditions is harsh.The reaction requires a long reaction time,a high reaction temperature,strong base equivalent and other strong conditions.From the synthetic and environmental considerations,there is an urgent need to develop a novel transition metal catalyst that is more environmentally benign and environmentally friendly for the synthesis of N-methylated amines.It designed Cp*Ir complex bearing a functional 2,2-bibenzimidazole ligand,the catalyst has high catalytic activity.Furthermore,such complex was found to be a highly effective and general catalyst for the N-methylation of a variety of amines with methanol in the presence of 0.3 equivalents of CS2CO3 and 120 ? for 12 hours.The catalytic system has successfully overcome the harsh conditions of strong base,high temperature,or long term reaction.This catalytic system is suitable for a wide range of substrates,not only for aromatic amines,but also for aliphatic amines.This reaction by-product is water and environmentally friendly.Reactive atom economy is high such reactions meet the requirement of green chemistry and have broad prospects for development.