Research On The Construction Of Nitrogen-containing Compounds Based On Three-component Tandem Reactions

Nitrogen containing compounds have a wide range of applications in chemical research and many cross-cutting fields including medicinal chemistry,natural product chemistry,agronomy,and materials science.Therefore,the development of simple,efficient,and green methods to construct nitrogen-containing compounds is still highly desirable..This thesis involves the synthetic methods for the construction of nitrogen-containing compounds including 1,2,3-triazoles,thiocarbamates,and?-ketoamides.These compounds as key structural units are widely existed in various natural products,physiologically active molecules,and drug molecules,which exhibit a wide range of biological activities and have important application value in medicinal chemistry.In recent years,these compounds have attracted widespread synthetic interests from organic chemists and medical scientists,and some synthetic strategies have been developed.However,the traditional methods suffer from some limitations such as the use of heavy metal salt catalysts,tedious operations to prepare raw materials,poor substrate scope,and harsh reaction conditions.Multi-component tandem reaction provides an ideal strategy for chemists to synthesize complex molecules,which has the advantages of simple operation,high reaction efficiency and high atom economy.In this thesis,we have developed the effective methods for the construction of N-1 and N-2 alkoxy substituted 1,2,3-triazoles,thiocarbamates and?-ketoamides through the three-component tandem reaction.The detailed overview is demonstrated as the follows:1.A copper-catalyzed three-component tandem reaction of alkyne(alkynic acid),azide trimethylsilane,and ether has been developed to selectively synthesize N-1 and N-2 alkoxy substituted 1,2,3-triazoles.The present method provides an efficient and convenient approach to access various types of N-1 and N-2 alkoxy triazoles at 80?by using of cheap copper salts as a catalyst and tert-butyl hydroperoxide as an oxidant It should be noted that the selective synthesis of N-1 or N-2 alkoxy 1,2,3-triazoles can be achieved by adjusting the catalyst loading2.The method to construct thiocarbamates has been developed through iodine catalyzed three-component reaction of sodium sulfinate,isocyanate and water.This methodology provides a simple,efficient,and green strategy for the construction of thiocarbamates by using of sodium sulfites as odorless sulfur source iodine as a non-metalcatalyst,and dimethyl phosphite as a reducing agent3.An efficient visible-light-promoted approach for preparing ?-ketoamides from?-oxocarboxylic acids,isocyanides and water is developed.The present photocatalytic protocol offered a simple and practical approach to produce a variety of ?-ketoamides,which has the advantages of the use of cheap Rose Bengal as photocatalyst,air as the green oxidant,and visible-light as the sustainable energy.Preliminary mechanism studies revealed that the reaction involved the sequential decarboxylation,radical addition and hydration processesIn summary,this thesis involves the synthetic methods for the construction of N-1 and N-2 alkoxy substituted 1,2,3-triazoles,thiocarbamates,and ?-ketoamides via the three-component tandem reactions.Compared with traditional methods,this strategy has the advantages of environmentally bengin conditions,cheap raw materials,broad substrate scope,good efficiency and high selectivity...