Synthesis Of Substituted Oxindoles From Secondary α-Bromo-Propionanilides Via Palladium(Ⅱ)-Catalyzed Intramolecular Cyclization

Oxindoles,also known as 2-indoles,is a very important class of benzo heterocyclic compounds.Oxindoles skeleton is widely found in natural products,bioactive substances and drugs.In recent decades,the synthesis of oxindoles skeleton has made great progress,which has laid a good foundation for its application in the field of drug research and development.However,the complicated prefabrication process and complex reaction conditions greatly limit the practical application of this kind of reaction.It is of great scientific significance and application value to develop a fast,simple and new synthetic strategy for the construction of oxindoles skeleton.Therefore,our research work is focused on the development of a method for the construction of oxindoles framework by intramolecular ring closure in transition metal catalysis based on α-halocarbonyl compounds with diverse structure and easy preparation.This paper mainly involves the following aspects:(1)A review of the synthesis of substituted oxindole derivatives,alkylation or arylation of haloalkanes.(2)A novel synthesis of substituted oxindole was reported.In this reaction,α-halocarbonyl compounds are condensed by corresponding aniline and carboxylic acid,followed by α-bromination to obtain various α-bromopropanoanilide substrates,and finally to obtain palladium-catalyzed molecular cyclization products.In this system,the structure of α-bromophenylpropanilide was easily prepared and modified,palladium acetate was used as the catalyst,tri(4-trifluoromethyl)phenyl phosphine was used as the ligand,sodium bisulfite was used as the base,and oxindole framework was constructed rapidly and efficiently in 1,4-dioxane.The reaction conditions are simple and the substrate is universal,which provides a new way for the synthesis of substituted oxindole.