Synthesis Of N-containing Heterocyclic Compounds And The Decarboxylation-Decarbonylation Of ?-Oxo Acids Via Photocatalysis

During the past several years,visible light photocatalysis has attracted a great deal of attention from researchers in organic synthesis.Harnessing of energy from visible light as an inexpensive and abundant means to construct complex organic molecules has emerged as a promising method in organic chemistry.And,nitrogenous heterocyclic compounds are widely found in nature.We envisioned that the construction of nitrogenous heterocyclic compounds from easy accessibility of raw materials might also be realized through visible-light photoredox catalysis under mild conditions.This thesis is mainly incudes the following five parts.Chapter 1: Synthesis of N-containing heterocyclic compounds via photocatalysis.Firstly,we briefly generalized visible light photoredox processes and the common photoredox catalysts.Secondly,we introduced the application of visible light photoredox catalysis for facilitating the formation of nitrogenous heterocyclic compounds.Chapter 2: Intramolecular 1,5-H transfer reaction of aryl iodides through visible-light photoredox catalysis: a concise method for the synthesis of oxindole scaffolds.We developed a visible-light photoredox catalysis approach to achieve the intramolecular 1,5-H transfer reaction of o-anilide aryl iodides.In contrast to conventional methods,this approach does not require superstoichiometric quantities of toxic reagents.Furthermore,this reaction features operational simplicity,mild reaction conditions,exceptional functional group tolerance and good to excellent yields.Therefore,the method described herein makes a significant complementation to the research fields of HAT reactions and photoredox catalysis.The practicability of this transformation has also been demonstrated in the more concise formal synthesis of(±)-coerulescine and(±)-physovenine in comparison with previous work.Chapter 3: Photoredox-induced intramolecular 1,5-H transfer reaction of aryl iodides for the synthesis of spirocyclic ?-lactams.We developed a photocatalysis method for the synthesis of ?-spirolactams through a tandem intramolecular 1,5-HAT reaction-cyclization process.A variety of novel ?-spirolactams were prepared from o-anilide aryl iodides in good to excellent yields.Further more,the methodology reported here features mild reaction conditions and exceptional functional group tolerance.And ?-terpinene,which is a commercially available reagent,has been applied to this transformation as a new hydrogen atom donor.We anticipate that this method will find broad application in the field of pharmaceutical sciences.Chapter 4: Photoredox-induced functionalization of alkenes for the synthesis of substituted imidazolines and oxazolidines.We developed a direct and concise approach to achieve the visible light photoredox-induced functionalization of alkenes for the synthesis of imidazoline and oxazolidine derivatives.This method achieved a one-pot,three-component cascade reaction through the combination of photoredox catalyzed radical addition and formal [3+2] annulation.In contrast to traditional methods,the advantages of this transformation are good to excellent yields,mild reaction conditions,operational simplicity and easy accessibility of raw materials.Chapter 5: Direct decarboxylative-decarbonylative alkylation of ?-oxo acids with electrophilic olefins via visible-light photoredox catalysis.We developed the visible-light photoredox catalysis to achieve the decarboxylative-decarbonylative alkylation of ketoacids with electron-deficient olefins.A series of quaternary carbons and ?-ketoesters have been directly constructed by the photoredox 1,4-conjugate addition of the corresponding alkyl ketoacids with electrophilic alkenes.The decarbonylation of primary,secondary and tertiary alkyl-substituted acyl radicals was investigated.Mechanistic studies of the transformation were also performed and a plausible reaction mechanism was proposed.