Development And Application Of Gold(Ⅰ)-Catalyzed Etherfication,Disproportionation And Tandem Cyclization Of Indole-Ynamides

Gold was developed into an excellent transition metal catalyst in recent years,gold catalyzed transformation was very popular in the field of chemistry with the advantages of mild reaction conditions and high synthetic efficiency.This thesis describes the development and application of gold catalyzed etherification,disproportionation and indole-ynamides tandem cyclization reactions,which demonstrated the properties of gold catalysts as Lewis acids and πacids.Ethers,as stable protective groups,play an important role in organic synthesis and have many classical synthetic methods.Therefore,we described our efforts to prepare unsymmetrical ethers using alcohols as alkylating reagents.This method is a new and green strategy in neat conditions for introducing alcohol protecting groups in organic synthesis,which use microwave as the reaction energy.Furthermore,Ph3PAuNTf2 is commercially available and is efficient at very low catalyst loadings.The method provides a rapid and straightforward access to benzyl,PMB,tert-butyl and trityl ethers with a wide range of substituents.During the mechanism study,the oxygen-18 isotope labeled experiments of benzyl alcohol and the kinetic curves of the reaction on benzyl alcohol with 2-phenylethanol were carried out,these results showed that the gold catalyzed asymmetric ethers synthesis proceed a classical SN1 type mechanism.Based on the study of gold catalyzed the etherification of benzyl alcohol and trityl alcohol.A new cascade oxidation reaction proceed etherfication and disproportionation was developed.Meanwhile we compared the FeCl3·6H2O with Ph3PAuNTf2 on the formation of trityl benzyl ether,the result indicated that the noble metal-gold could be replaced by the sustainable metaliron.The influences of benzyl and trityl alcohols substituent effects on the etherification and disproportionation reactions were studied.The deuterium crossover experiment proved that during the disproportionation the hydride transfer might occur in an intermolecular mannner.A new gold catalyzed tandem cyclization of indole-ynamide strategy was developed for the pentacyclic indoline scaffold.Based on the successful of the model study,the indoleynamide substrate was modified continuously.As expected the pentacyclic indoline alkaloid skeleton was achieved.This work provided a good foundation for the total synthesis of indole alkaloid with the same scaffold.