New Catalysts for Cis-Selective Metathesis: Agostic Interaction and Meso-N-Heterocyclic Carbenes

本项目将合成新型的烯烃歧化顺式选择性催化剂。本项目将采用两种新的、尚未探索的方法：(1)利用早期过渡金属Fischer卡宾络合物中的agostic相互作用来指导enyne交叉复分解反应的选择性。特别是，我们打算在潜水员小组研究烯炔复分解时所学到的基础上，提高催化剂的稳定性。(2)在N-杂环卡宾设计的基础上，我们将在中位-N-杂环卡宾的一侧构筑芳香族‘墙’来控制催化剂在Ru-卡宾中的选择性。目前，烯烃歧化反应是催化碳-碳双键构筑最有效的方法之一，已被化学家广泛应用于多个领域。尽管复分解化学取得了巨大的成功，但主要的限制是对双键几何结构的控制：顺式双键不能选择性地生成。这个项目的重点是通过开发催化剂来解决顺式选择性问题。通过这个奖项，有机和高分子化学项目支持纽约州立大学布法罗分校化学系的Steven T.Diver教授的研究。Steven Diver教授致力于开发新的环的复分解方法，研究烯炔复分解反应的催化机理，以及开发新的卡宾催化剂。这一三管齐下的努力影响了我们对金属卡宾反应性基本方面的理解，并导致了某些合成应用中选择性的提高。新型卡宾催化剂的开发有望提高顺式选择性，并使人们更好地了解哪些因素对选择性起关键作用。复分解方法是高效的，使用少量的Ru卡宾催化剂(称为格拉布斯卡宾)，广泛适用于合成小分子(如药物)和聚合物结构(如纳米材料)。新型催化剂的成功开发将对制药行业的合成产生影响，从而提高药物生产的效率。

This project will synthesize new catalysts for cis-selectivity in olefin metathesis. Two new, unexplored approaches will be taken in this project: (1) Use of agostic interactions in early transition metal Fischer carbene complexes to guide selectivity in enyne cross metathesis. In particular, we intend to improve the catalyst stability building upon what we have learned previously in the Diver group while studying enyne metathesis. (2) Building on N-heterocyclic carbene design we will construct an aromatic 'wall' on one side of meso-N-heterocyclic carbenes to control catalyst selectivity in ruthenium carbenes. Currently, the olefin metathesis provides one of the most effective methods for catalytic carbon-carbon double bond construction, and has been widely used by chemists in many fields. Despite the huge success of metathesis chemistry, the major limitation is control of double bond geometry: cis-double bonds cannot be made selectively. This project is focused on this cis-selectivity problem through catalyst development.With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Steven T. Diver of the Department of Chemistry at the State University of New York-Buffalo. Professor Steven Diver's research efforts center on the development of new metathesis methods for the synthesis of rings, the study of the catalytic mechanism of enyne metathesis and the development of new carbene catalysts. This three-pronged effort has impacted our understanding of fundamental aspects of metal carbene reactivity and led to improvements in selectivity in certain synthetic applications. Development of new carbene catalysts is expected to enhance cis-selectivity and lead to a better understanding of which factors are critical to selectivity. Metathesis methods are highly efficient, using small amounts of ruthenium carbene catalysts (known as the Grubbs carbenes) and are widely applicable to the synthesis of small molecules (such as pharmaceuticals) and polymeric structures (such as nanomaterials). Successful development of new catalysts will have an impact on synthesis in the pharmaceutical sector, leading to improved efficiency in drug production.