Research On Oxygen-Involved C-X Bonds (X=C,O,S,Se,Te)Construction Reactions

Oxidization reactions play an important role in production and life,and the oxidization reaction with oxygen is a significant part.Oxygen,as a green oxidant,is widely used in organic chemistry,on account of its high atomic economy,low cost,pollution-free and other characteristics.At present,the oxidization reactions with oxygen are classified as oxidative coupling,transition-metal catalyzed oxidization,light-catalyzed reactions and carbon-carbon bond breaking reactions.The oxidation reaction with oxygen has been remarkably developed,but to exploit new methods for oxidization with oxygen is still a research hotspot.Therefore,with the help of the green oxidant oxygen,I have completed the following projects respectively.1)Construction of C=O and C=C bonds with oxygen------synthesis of isatins and isoindigos:Extra oxidant usch as I₂ or PIDA are usually used in the methods for synthesis of isatin by oxidization of indole or indolone,which results in the formation of additional by-products.Refluxing in acid conditions for a long time and low yields is often needed in the protocols for synthesis of isoindigos.To avoid the above deficiencies,we exploied a reaction for syntheses of isatins and isoindigoes,using NaI as the additive,O₂ as the oxidant.A series of isatins were obtained in THF.However,isoindigos,the diploymer of isatins,were gained with good selection when THF was replaced by DMSO.Furthermore,this protocol provide a powerful support for experimental verification of“oxidation relay strategy”proposed by our group earlier.We believe that this method may provide a concise and efficient protocol for synthesis of isatins and isoindigos,which could be widely used in organic chemistry,medicinal chemistry,materials chemistry and dye industry.2)Construction of C-S/Se/Te bonds with oxygen------desulfuration of aryl disulfides to generate the aryl sulfides:The approaches for synthesis of aryl thioether mainly include coupling reaction catalyzed by transition-metal,C-H bond functionalization and nucleophilic substitution.But many of these methods have several deficiencies,such as:harsh conditions,difficulty escaped directing group and narrow substrate scope.Therefore,exploiting CuI as the catalyst,phenanthroline as the ligand,and K₂CO₃ as the base,the desulfuration of aryl disulfides to generate the aryl sulfides under oxygen atmosphere was achieved.This approach has broad substrates scope and excellent functional group tolerance.It is even compatible with several sensitive groups such as alkene,ketone,ester,amide,cyanide,alkene,nitro and methylsulfonyl.With the help of this reaction,we have synthesized 82 correlative products including challenging bowl-shaped organic materials with great ring tension.The powerful strategy holds promise for the discovery of biological sulfur-lead compounds,sulfur-containing medicine and functional organic materials synthesis.