IBX-mediated Cyclization Of Indole Derivatives And Spirocyclization Reaction Of Amino Acid Derivatives

Organic hypervalent iodine reagents are chemically similar to transition metals,and the reactions they promote are characterized by mild conditions,high selectivity,good yields,and environmental friendliness,and therefore,organic hypervalent iodine reagents are widely used in organic synthesis.2-iodoxybenzoic acid（IBX）,a green organic hypervalent iodine reagents,can selectively oxidize alcohols to carbonyl groups,and other oxidation reactions promoted by it have been found,and in addition IBX is involved in another major class of oxidation reactions in which IBX is involved is through oxygen transfer to substrates.In view of the importance of IBX as an oxidation reagent,this chapter reviews the research and applications of o-iodoylbenzoic acid in organic synthesis in recent years.The second chapter of this thesis deals with the synthesis of polycyclic spiroindoles by cascade cyclization catalyzed by IBX.We report a IBX-mediated intarmolecular oxidative spiro-fused tandem cyclization reaction of tryptophan analogs bearing an N-arylamides side-chain to rapidly afford polycyclic spiroindolines featuring multiple stereocenters including a quaternary stereocenters under mild reaction conditions.Among them,a novelty azaphosphol idine-containing spiroindoline compound is synthesized for the first time.It may open the door to azaphos pholidine-containing spiroindoline compound of potential interest in synthetic and medicinal chemistry.A plausible mechanism is proposedThe third chapter investigates the in situ spirocyclization reactions of aminoquinoline-protected amino acid derivatives.Spirocyclic compounds usually exhibit a wide range of biological activities,and among the many spirocyclic compounds,spirocyclohexadienones are present as substructures in many natural products,drugs,and other compounds with a variety of uses,thus attracting wide interest among synthetic organic chemists.Aromatic ring dearylation is one of the most straightforward methods for spirocyclic skeleton synthesis.In recent years,the intramolecular in situ cyclization method has gained much attention in organic synthesis,as it provides an efficient way to form new carbon-carbon and carbon-heteroatom bonds.In this paper,we describe in detail the oxidation of aminoquinoline or aminonaphthalene protected amino acid derivatives to spirocyclic imidazolones under a mixture of HFIP and H₂O solvents using o-iodobenzoic acid as the oxidant.This method,with milder conditions and a wide range of substrate applicability,lays the foundation for further extension of the oxidative synthesis of spirocyclic imidazolones with hypervalent iodine reagents.