辉铜矿催化合成双吲哚甲烷性能及反应机理

Catalytic Activities and Reaction Mechanism of the Synthesizing Bis(indolyl)methanes over Chalcocite

针对双吲哚甲烷合成尚存在释放有害物质、需贵金属作为催化剂等问题,研究了“辉铜矿/过氧化氢”耦合体系催化N甲基吲哚与N,N二甲基乙酰胺反应,实现双吲哚甲烷绿色合成新方法。经对铜矿种类、氧化剂类型等影响反应因素进行筛选,得到合适反应条件为:N甲基吲哚0.5 mmol、N,N二甲基乙酰胺1.0 mL、辉铜矿20 mg、30%过氧化氢1.0 mmol、反应温度140℃、反应时间4 h。在此条件下,催化剂可循环使用6次而不失活性,并得到9种3,3’二N烷基取代吲哚甲烷,产率为82%~95%。根据控制实验结果与相关文献,提出了N,N二甲基乙酰胺经单电子转移,并与N甲基吲哚进行亲电反应的机理。该方法为双吲哚甲烷类物质绿色合成提供理论基础及技术支撑。

Bis(indolyl)methane is a very important compound,but its synthesis can release harmful substances and requires precious metals as catalysts.The combination of chalcocite/hydrogen peroxide could promote the reaction of N-methylindole and N,N-dimethylacetamide,achieving new and green synthesis of bis-substituted-indolylmethanes.After screening conditions including copper ore type,oxidant type and other factors,the suitable conditions were obtained:0.5 mmol N-methylindole,1.0 mL N,N-dimethylacetamide,20 mg chalcocite,1.0 mmol 30%hydrogen peroxide,reaction temperature 140℃,and reaction time 4 h.Under the optimal reaction conditions,it found that chalcocite can be run for 6 times without losing the activity,and N,N-dimethylacetamide can react with different substituted indoles to form 9 bis-substituted-indolylmethanes with yields ranging from 82%to 95%.Moreover,on the basis of control experiments and referring to relevant literatures,the reaction mechanism was proposed:N,N-dimethylacetamide underwent single electron transfers steps,following to electrophilically attack N-methylindole to form the product.Above all,this strategy provides theoretical basis and technical support for the green synthesis of bis-indole methane compounds.