环状骨架广泛存在于天然产物及人工合成的医药、农药、功能材料分子中，因此高效构建这些骨架的方法学研究具有重要的理论和应用价值。本项目利用氮杂环卡宾(NHC)能使醛基发生极性反转这一独特性质，将重点开展基于NHC催化的新型串联反应的高效构建环状骨架的方法学研究：一是在NHC 催化的Stetter 反应和安息香反应参与下，通过多组分串联反应，实现二芳基化杂环化合物的高效合成；二是设计合成多反应位点底物，寻找有效的NHC催化剂，经过串联反应构建重要环状骨架；三是通过计算有机化学手段解释反应机理，探究NHC的结构与催化活性、反应选择性三者关系，为催化剂的设计提供有效指导。本项目的实施将不仅为重要环状化合物的合成提供高效、立体选择性高、产物多样性高的方法，而且将凸显NHC在催化有机合成方面的独特性和优越性并拓展NHC在有机催化领域的应用范围，同时也为新的具有潜在应用前景的环状化合物的发现奠定基础。

Developing new synthetic methods and reaction systems for the efficient erections of cyclic skeletons is of great theoretical and practical significance, due to the extensive distribution of these scaffolds in natural products, medicine, agrochemical and functional materials. By use of the unique umpolung reactivity of aldehyde under the catalysis of N-Heterocyclic Carbene (NHC), this project will focus on the development of new NHC-catalyzed cascade reactions and their applications in the efficient assembly of cyclic scaffolds. Firstly, some diarylated heterocycles will be synthesized efficiently via NHC-catalyzed multi-component cascade reactions incorporating Benzoin and Stetter reaction. Secondly, some designed substrates with multiple reactive sites will be synthesized and react with other reagents to fabricate the cyclic scaffolds under NHC-catalysis. Thirdly, the reaction mechanism and the relationship among the structure of NHC, catalytic activity and reaction selectivity will be studied to provide effective guidance to the design and synthesis of catalysts with the assistance of computational organic chemistry. This study will not only pave efficient avenues to the diversified and stereoselective construction of important cyclic frameworks, but also highlight the uniqueness and superiority of NHC as organocatalysts. At the same time, this research will broaden the application scope of NHC in organocatalytic synthesis and lay a foundation for the discovery of new cyclic compounds with potential application prospect..