Synthesis Of Pyran And Indol Derivatives Catalyzed By Piperidine/copper(?)

One of the most important reaction in organic synthesis is cyclization.It is a potent method to construct Oxygen and Nitrogen contained heterocycles.And always this synthetic strategy is a hot topic in organic synthesis to improve cyclization efficiency through organo-or metal-catalyzed Oxygen and Nitrogen contained heterocycles.Cycloaddition is one of crucial sub-type of cyclization.Cycloaddition reaction have the ability to provide multiple bond formations[1,2].Formal cycloaddition is a stepwise reaction.On the view of mechanism,formal cycloadditon is accomplished step by step which is the difference from cycloaddition.We synthesized Oxygen contained heterocycles---pyran derivatives from ?,?-unsaturated aldehyde with 1,3-diketone equivalents in the presence of secondary amines as organocatalyst.And this reaction is in the name of formal O-[3+3]cycloaddition.Pyran and benzopyran which were core fragments occurred in many natural products,bioactived compounds could be generated through this formal O-[3+3]cycloaddition,thus we sought a synthetic strategy catalyzed by organocatalyst to construct pyran and benzopyran contained natural products.Using this formal O-[3+3]cycloaddition methology,the total synthesis of oxygen contained heterocycle natural products---Paraensidimerine family involed Paraensidimerine A,C',F and F' were accomplished in two steps.In our further study of organocatalyzed formal O-[3+3]cycloaddition,construction of benzopyran was accomplished in one step directly instead of cyclization and aromatization.And this advanced organo amine catalyzed formal O-[3+3]cycloaddition was applied in the total synthesis of benzopyran contained natural products,involed Clusiacyclol A and B,iso-Eriobrucinol A and B,Eriobrucinol.Metal catalyzed cyclization is another vital aspect of this reaction.A variety of nitrogen contained heterocycles could be prepared through this synthetic strategy.It is always attractive to prepare indole since it is one of the most widespread nitrogen contained heterocycles naturally and exhibits excellent bioactivity.Copper-catalyzed cyclization for the synthesis of diindolylmethanes was described here.And our metal catalyzed cyclization method is economical and has potential pratical value.