Vinyl Aziridines Participated Asymmetric Cycloadditions Catalyzed By Rhodium

Chiral N-heterocycles are valuable skeletons found in an array of natural products and pharmaceuticals with diverse biological and medicinal properties.Considerable attention has been paid on the development of more efficient preparation of these compounds.Among them,cycloadditions are particularly attractive for their remarkable efficiency and convergence in synthesis of these compounds with 100%atom utilization.Vinyl aziridines,the small nitrogen-containing heterocycles,are increasingly being exploited as versatile building blocks in organic synthesis because of the ring strain associated with the three-membered ring and the carbon-carbon multiple bond,which can participate in reactions and stabilize charges and radicals formed.Therefore,we choose vinyl aziridines to serve as activated synthons in rhodium-catalyzed cycloadditions.The synthesis of chiral heterocycles in an enantioselective manner has been achieved by a chirality-transfer strategy.There are three parts in this dissertation:in the first part,we have demonstrated that vinyl aziridines can serve as new aza-3C synthons in rhodium-catalyzed aza-[4+3]cycloaddition reactions with silyl dienol ethers.The reaction provides an efficient,straightforward and atom economic route to highly functionalized azepine architectures;in the second part,the first rhodium-catalyzed[(aza-3C)+(aza-3C)]cycloaddition of vinyl aziridines with C,N-cyclic azomethine imines has been achieved,providing high sp~3-content 1,2,4-hexahydrotriazines in moderate to high yields with extremely excellent diastereoselectivities;in the third part,we have demonstrated a highly enantioselective and diastereoselective[3+2]cycloaddition of vinyl aziridines with silyl enol ethers catalyzed by rhodium,providing an efficient approach to synthesize functionalized pyrrolidines.Thus,?-amino ketone can also be constructed by changing some reaction parameters.