Intramolecular [3+2] Cross-Cycloadditions Of Cyclopropanes1,1-Diester With Alkene And Epoxides And Total Synthesis Of Natural Product Phyllocladene

Bridged ring skeleton is a class of very important molecular skeleton, and widely present in the natural product. Bridged ring skeleton contains carbocyclic skeletons and heterocyclic bridge ring divided according to different classification methods. We here mainly investigation synthesis and application of these two types of important bicyclic skeleton:bridged [n.2.1](n=2,3,4) carbocyclic skeletons and bridged [n.2.1](n=3,4) heterocyclic skeleton.In the past100years, Organic synthetic chemists has developed a number of methods to build these two types of ring systems. In recent years, with some important physiological activity of natural products such as GB.13and Platensimycin, Englerin A, etc. are constantly being isolated, the bridged ring skeleton building method and related total synthesis of the natural product is still the field of organic synthesis popular topic. Cycloadditions, especially the intramolecular cycloadditions with highly bonding efficiency, good regional and stereo selectivity, play an important role in the construction of complex cyclic skeletons. Our study based on intramolecular cross-cycloaddition or rearrangement cycloaddition reactions of cyclopropane with an unsaturated bond or the strained rings to development of general and efficient method of constructing bridge skeletons, at the same time expanding its applications in terpenoids and complex natural products.We have developed a novel intramolecular [3+2] cross-cycloadditions of cyclopropanes-1,1-diester with alkene. These reactions provided a general and efficient strategies for construcitions of bridged [n.2.1](n=2,3,4) carbocyclic skeletons and were successfully used to the total synthesis of Phyllocladane. At the same time, intramolecular [3+2] cross-cycloadditions of cyclopropanes-1,1-diester with epoxides,.These reactions provided a general and efficient strategies for construcitions of oxa-[n.2.1](n=3,4) bicyclic skeletons. These two types of intramolecular cross-cycloadditions can be catalyzed by Lewis acid, and the second type of reaction also can be catalyzed by protonicacid. all proceed on mild reaction conditions and have the broad scope of the substrates and have a diverse product structures. We have gradually established the diversity of molecular libraries of these two types of bridged skeletons, which will has laid a solid foundation for the later discovered new medicine and pesticide lead compound.