Studies On Transition Metal Catalyzed [5+2] Cycloaddition Reaction Of Imidazolidines And Allenamides

Heterocyclic compounds,especially diaza heterocyclic compounds,are common backbones for natural products and drugs,so the rapid construction of these structures has long been the research of organic chemists.Besides the related total syntheses,the synthetic methods include metathesis,cyclization,rearrangement and other reactions.Although chemists are still exploring simple and efficient synthesis methods,the current methods suffer some limitations,such as starting materials that need to be prepared in multiple steps and harsh reaction conditions.Based on the above research,the authors found that the bench-stable and readily available imidazolines can be regarded as 1,5-dipoles that can react with allenamides via formal [5+2] dipolar cycloaddtions under transition metal catalysis.This thesis includes the following three chapters:The first chapter introduces the cycloaddition reaction and the transition metal catalyzed allenamide cycloaddition reaction.First,the cycloaddition reaction is an important method for the synthesis of(hetero)carbocyclic compounds,especially the medium and large ring systems.The dipolar cycloaddition is one of the most important cycloaddition reactions that can take place under heating,illumination or transition metal catalysis.Second,the transition metal catalyzed cycloaddition reaction of allenamides is introduced.The nitrogen atom on allenamides has an electron-donating effect,which not only improves the reactivity of the central carbon atom,but also makes allenamides more reaction possibilities and regional selectivity.In the second chapter,the [5+2] cycloaddition reaction between imidazolines and allenamides catalyzed by transition metals was mainly studied to selectively generate two diaza heterocyclic systems: under gold catalysis,the [5+2] cycloaddition reaction took place to generate 1,4-diazepanes;under iron catalysis,a highly stereoselectivitive [5+2]cycloaddition/Friedel-Crafts cascade reaction happened to provide novel 1,4-diazabicyclo[4.3.1]decanes.The reaction conditions were optimized,and a series of products were obtained with excellent yield and selectivity.In addition to allenamides,the authors also evaluated the other types of allenes including alkoxyallens,allenoates and unbiased allenes.The alkoxyallenes could obtain the target product.Besides imidazolines,hexahydropyrimidines were also tested and can obtain the corresponding [6+2] cycloaddtion products.Moreover,a series of control experiments and deuterated experiments were conducted,which demostrated that water plays as a proton transfer catalyst during the reaction.In the third chapter,supporting information is described.This thesis mainly elaborates on the basic experimental procedures and data characterization of compounds in this study.