TEMPO Catalyzed Oxidative Desulfitative C─N Coupling Reaction Using Molecular Oxygen at Room Temperature

ABSTRACT

Oxidative organic transformation has emerged as a powerful strategy for C─C and C–heteroatom bond forming reaction. In this study, a completely metal free, oxidative desulfitative C─N coupling has been realized harnessing C─S bond as the electrophilic partner at room temperature in eco‐benign solvent ethanol. The thio‐amide group present in 5‐isatinylidene‐rhodanine has been utilized as a source of C─S bond. C─N coupling with amine is realized using TEMPO as an organo‐catalyst. Molecular oxygen has been exploited as the terminal oxidant. No additives or strong base are required for this reaction. Notably, this C─N coupling occurs at room temperature avoiding dry solvent or inert atmosphere. The pure product can be obtained just by filtration and recrystallization from ethanol. This significantly minimizes the use of toxic organic solvents. The protocol is extremely reproducible and product yields are very high. All these features make this transformation environmentally benign and very much pertinent for the construction of C─N bonds in a sustainable way.