Photoredox Catalysis:Visible-Light-Induced Azotrifluoromethylation Of Alkenes

Visible light induced organic synthesis has enjoyed a rapid development during past decade and received extensive attention from synthetic community because of the feasures of adequate energy sources?green chemistry of the reaction?simplicity of the operation?the mild reaction condition and the strong applicability and so on.On the other hand,because of the advantage of construction of two C-C bonds or C-X(H or heteroatom,halogen)bonds by one step reaction operation,difunctionalization of alkenes has become an efficient method to mass chemical conversion and fine chemical synthesis.Undoubtedly,realization of difunctionalization of alkenes by the strategy of visible light induced photoredox catalysis has a very important significance.According to the literatures report,introduction of CF3 group into molecule has a big difference on its physical properties,chemical properties and biological activities,incorporated the CF3 group into the specific fragments of specific molecules effectively has aroused wide interest of organic synthetic chemists,drug scientists,and materials scientists.In view of this,we have designed and realized a visible-light-induced azotrifluoromethylation of alkenes with alkenes?Langlois' reagent and aryldiazonium salts as the starting materials,finally,we obtained the products combined CF3 group and azo group into one molecule.Firstly,We have got the optimal reaction condition:0.5 mol%Ru(bpy)3Cl·6H2O complex as photocatalyst?7 W Blue LEDs as light source?Langlois' reagent as CF3 group source?aryldiazonium salts as azo group source and 4A MS as additive by screening several reaction paramerets such as solvents?photocatalysts and light sources.With the best condition in hand,we successfully obtained a range of diversely substituted?-trifluoromethyl azo compounds with 34%-92%yield within 40 min under room temperature.At the same time,we have tried some synthetic transformations of the desired azo compounds and obtained the important desired ?-trifluoromethylamine derivatives and CF3-containing indole derivatives with 86%and 95%yield,respectively.Finally,we have proposed the possible mechanism for this reaction based on preliminary mechanistic studies and reported literatures and studied the transformation of trans-and cis-azo products preliminary.We have also fully characterized all the desired products by NMR?HRMS?IR?M.P.and X-ray crystallography analysis.The above experimental results has been published on Chem.Commun.(2016,DOI:10.1039/C6CC03335K),and this methodology would provide a new way to achieve difunctionalization of unactivated alkenes under mild condition.It also would furnish an synthetic intermediate for the synthesis of nitrogen-containing compounds with potential biological activity.