Tandem Reaction Of Arylhydroxylamines With Hypervalent Iodine Reagents

Arylhydroxylamine compounds are an important type of reaction substrates in organic synthesis and they are widely used in the synthesis of pesticides,medicines,polymerization inhibitors,antioxidants,cosmetics,etc.For example,Bamberger rearrangement reactions can be used to synthesize substituted aromatic hydrocarbons.The active ingredients of crop protection agents can also be synthesized by acylation and alkylation of arylhydroxylamine compounds.Because it contains-N-OH groups,it can also be used as an electron transfer carrier for biological enzyme reactions,therefore,such compounds have broad application prospects.Hypervalent iodine reagents have attracted great attention from chemists in recent years because of their advantages of easy preparation,good stability,low-toxicity,high reactivity,and their excellent performance and unique applications in several chemical transformations.It has become one of the research hotspots in the field of organic chemistry Hypervalent iodine reagents generally exhibit electrophilicity in the reaction,and it can react with some nucleophiles with strong nucleophilicity without metal catalysis,and aryl iodide,which is the by-product of the reaction,can also be recycled.Thus,hypervalent iodine reagents have gradually become important reagents in organic chemistry.Indole and its derivatives are an important type of heterocyclic alkaloids with good biological activity and it can be widely used in the fields of medicine,industry and agriculture.Its market demand is growing rapidly and the development prospect is broad.More and more research related to the synthetic methods of indole compounds,were reported in the literature.Most of the reaction conditions are complicated and harsh.For example,high temperatures,strong acids,or expensive metal catalysts or ligands are required.Therefore,it is still necessary to develop new methods and new strategies for indole synthesis starting from cheap materials and under mild conditions.Axial chiral compounds are commonly found in many important biologically active molecules and they are the core skeleton of many chiral catalysts and chiral ligands.Therefore,the synthesis of biaryl compound’s has been the focus of chemists all the time.In the past,for the construction strategy of the biaryl skeleton,it is mainly relied on the transition metal-catalyzed cross-coupling reactions and the arene C-H bond arylation reactions.Many reactions are relatively restricted to special substrates and harsh reaction conditions.Therefore,we hope to develop some novel synthetic methods of biaryl compounds from cheap materials and under mild conditions in order to expand the research content of axial chiral chemistry.The research contents of this thesis include the following four sections.Section Ⅰ,we developed a copper-catalyzed O-vinylation of arylhydroxylamine using vinyliodonium salts as vinylation reagents to generate a transient O-vinyl-N-arylhydroxylamine that rapidly undergoes a[3,3]-sigmatropic rearrangement and subsequent cyclization/rearomatization to form a substituted indole.A wide range of highly substituted indoles and benzoindoles can be afforded in good yields.This approach is readily scalable,and the scope and application of this process are presented.Section Ⅱ,we present a transition-metal free direct O-arylation of arylhydroxylamines employing diaryliodonium salts as arylation reagents to form transient N,O-diarylhydroxylamines that could subsequently undergo[3,3]-sigmatropic rearrangement and rearomatization to afford structurally diverse NOBIN analogs in good to excellent yields under mild conditions.This tandem approach is operationally simple and readily scalable and has great functional group tolerance.In addition,an NHC-catalyzed kinetic resolution/O-acylation of the racemic NOBIN analogs was successfully accomplished to access a diverse range of enantiopure axially chiral NOBIN analogs with excellent enantioselectivity.Section Ⅲ,a class of palladium-catalyzed C-H bond activation was proposed to synthesize polytriazole and polyisoxazole compounds with good substrate applicability and good yield.This reaction provides a practical way for the synthesis of different types of fused heterocyclic compounds.Section Ⅳ,an unprecedented copper-catalyzed intermolecular sulfur-sulfur bond insertion between aryldiazoacetates and benzenesulfonothioate has been successfully developed.Diverse a-disulfur functionalized esters were synthesized in good to excellent yields.The sulfur ylide formation and subsequent Stevens rearrangement are considered as the key steps for the discovered reaction.In summary,the synthesis of diverse indole compounds and biaryl compounds was achieved by[3,3]-rearrangement through the reactions of hydroxylamine compounds with different types of hypervalent iodine reagents.Based on the synthesis of biaryl compounds,we achieved the kinetic resolution of biaryl compounds.These studies not only provide new methods for the synthesis of polysubstituted indole compounds and biaryl compounds,but also play an important role in the fields of medicinal chemistry,chiral catalysis,and functional molecules synthesis.