The Transformation Of Vinylogous Imine Intermediates Based On Indole Skeleton

Substituted Indoles are important structures due to their wide distribution innatural products and biologically active molecules. Some of indoles are the corenucleus of many promising therapeutic agents, and the emergence of their structuresis more recent now. Though a variety of synthetic methods have been developed tothese compounds, considering the significance of this kind of compounds, a new andefficient synthetic method to these indole derivatives still remains a highly desirablegoal in synthetic chemistry.Vinylogous imine intermediate based on indole skeleton has been proved to be agood electrophilic specie and useful intermediate in indole transformations. It can begenerated using in either acidic or basic reaction conditions, which uponnucleophilic addition afford the corresponding substituted indoles. Several reactionsinvolved this intermediate have been reported, and the desired substituted indoleswere obtained conveniently.Focus on the synthesis of indoles and indole derivarites, this thesis describesour recent research on the transformation of vinylogous imine intermediate, and thisthesis contains the following four parts:In chapter1, some of the recent developments on the generation andtransformation of vinylogous imine intermediate are summarized.In chapter2, an efficient and facile approach to2,3-disubstituted indoles viareductive alkylation of simple2-substituted indoles with aldehydes or ketones usinghydrogen as a clean and atom economic reductant under ambient pressure wasdeveloped. The main advantages of this route are excellent yields, simple operationand purification procedures.In chapter3, an efficient Rhodium-catalyzed addition reaction of arylboronicacids to vinylogous imine intermediate generated in situ from sulfonylindoles wasrealized. This strategy provided a facile access to the relevant C3-sec-alkylsubstituted indoles in moderate to high yields with a wide range of substrates. Apreliminary study on the enantioselective version of this Rhodium-catalyzedaddition reaction of arylboronic acids to vinylogous imines was also examed, andpromising results were obtained.In chapter4, palladium-catalyzed addition of arylboronic acids to vinylogous imines generated in situ from sulfonyl indoles was successfully developed. Thismethod is an important complement to Rh(I)-catalyzed addition reactions we havereported recently and provides a potential and facile access to3-sec-alkyl substitutedindole derivatives.