Synthesis Of Thioether And Sulfone Compounds Via Transition Metal- Or Iodide-catalyst Through C-H Functionalization

Indolyl thioether groups are key structural units found in various biological active compounds, recently, many sulfenylindoles were reported possess activities of anticancer, antiviral, antioxidant. Undoubtedly, developing numerous practical methods to synthesis indolyl thioether have attracted increasing attention from synthetic chemists. Particularly, the C2-and C3-substituted of indole. For the past decade, although many useful methods had been used to sulfenylation at the C3-position of indole, that indirectly address these problems of regioselectivity chemistry, on the other hand, exploring more and more methods to synthesis sulfenylindoles become more serious every day. In recent years, major advances have been achieved in the C-H bond functionalization of indoles, unfortunately, the regioselective formation of C-S bonds at the C2 and/or C3 sites of indoles has not been explored much. For this purpose, we wanted to investigate the area immediately.The use of copper salt catalysts has been shown to be successful, because copper possesses the ability to alter single-and double-electron quantities through transformation of its four oxidation states:Cu0, CuⅠ, CuⅡ, and CuⅢ. Therefore, copper catalysts possess the ability to associate different functional groups through Lewis acid interactions or p coordination.With its inexpensive, low toxicity and abundance in nature, iron-catalysts have gained increasing interest in catalyst chemistry, some pioneering works to prove iron-catalysts possess Fe-2, Fe-1, Fe0, Fe1 and Fe2 five oxidant states to get the capacity of catalyze circular reactions, were exploited in synthetic studies. The character likes iron, nickel possess Ni-1, Ni0, Ni1, Ni2, Ni3 and Ni4 six oxidant states and various coordination modes, nickel seem has the potential to be a younger sibling of palladium to been used in transition metal catalysis, those has been proven by many scientific experiments.In recent years, radical reaction solution is well developed, the paper also discuss experiments and research discussion of free radical reactions, to a large extent solved the problems of indoles radical reaction at the C-S bond formation. In order to the future development of the radical reaction provides strong evidence.