A Concise Approach To The Indoles Via Oxidative C-H Amination Of 2-Alkenylanilines Using Dioxygen As The Sole Oxidant

Indoles are ubiquitous in natural products,especially the alkaloids.Most of them have vital activities.Indoles are important and valuable heterocycles also because their wide application in chemistry,biology,and material sciences.Therefore,the synthesis of indole derivatives has long been of great interest in organic synthesis.A great number of superior methods have been established,and a large portion of these methods employ transition metal catalysts.Though these protocols are efficient and have been widely applied in organic synthesis,new and more efficient synthetic methods still continue to be pursued.The intramolecular amination reaction of alkenes is a direct approach to indole synthesis and these approaches are known in the literature.A novel synthetic method to prepare indole derivatives from N-Ts-2-alkenylanilines has been achieved.This protocol is operationally simple and conforms to the atom economy.Since oxygen is very cheap,resourceful and produces no environmentally hazardous byproduct,and has been extensively applied in organic synthesis,we use oxygen as sole oxidant.Our research is mainly about:1.In order to optimize the reaction conditions,key operating parameters were examined.2.With the optimized conditions in hand,a series of indole derivatives have been synthesized.We test substituents' electronic effect and steric effect.3.Based on the results from previous literature and an array of control experiments,a plausible mechanism for this reaction was postulated.