Bimetallic Carbene Complexes as Reagents and Catalysts for Organic Synthesis

这项研究涉及开发新的方法来指导Fischer卡宾络合物的强大的碳-碳键形成化学，用于有机合成。它将集中在烯烃的环丙烷化和几种烯烃的加成/插入反应上。关键中间体是非双金属Fischer卡宾络合物，其中一个缺电子的金属中心连接到一个金属卡宾氧基的杂原子上。由于Lewis酸性金属取代基的缺电子性质和快速的配体取代化学，它将在这些双金属体系的化学中发挥四个方面的作用：(1)作为模板，在其上连接带有配体“手柄”的底物分子，以实现新的和有用的非对映选择性；(2)作为手性辅助剂的结合部位，实现不对称诱导；(3)作为分子内亲核反应性的来源，允许稳定的Fischer卡宾通过杂原子置换而被激活：和(4)作为一种手段，在温和的条件下再生卡宾部分，允许目标反应在催化条件下进行。化学部合成有机计划将支持弗吉尼亚大学化学系M.G.芬恩博士的研究。这项研究是在合成方法学领域，并将开发新的方法来指导碳-碳键的形成，这是有机化学中最重要的反应之一。这一过程中的关键中间体是异双金属Fischer卡宾络合物，它是包含两个不同金属原子的分子。这些中间体将能够对反应进行择形控制。

This research involves the development of new methods for directing the powerful carbon-carbon bond-forming chemistry of Fischer carbene complexes for the purposes of organic synthesis. It will focus on the cyclopropanation of alkenes and several addition/insertion reactions of alkynes. The key intermediates are heterobimetallic Fischer carbene complexes, in which an electron-deficient metal center is attached to the heteroatom of a metallocarbenoxy moiety. By virtue of their electron-deficient nature and rapid ligand substitution chemistry, Lewis acidic metal substituents will play a fourfold role in the chemistry of these bimetallic systems: (1) as a template on which to attach substrate molecules bearing a ligand "handle" to achieve new and useful diastereoselectivity; (2) as a site for attachment of chiral auxiliaries to achieve asymmetric induction; (3) as a source of intramolecular nucleophilic reactivity, allowing stabilized Fischer carbenes to be activated by heteroatom displacement: and (4) as a means to regenerate the carbene moiety under mild conditions, allowing the target reactions to be performed under catalytic conditions. %%% With this award the Synthetic Organic Program of the Chemistry Division will support the research of Dr. M. G. Finn of the Department of Chemistry at the University of Virginia. The research is in the area of syntheic methodology and will develop new methods for directing carbon-carbon bond formation, one of the most important classes of reactions in organic chemistry. The key intermediates in the process are heterobimetallic Fischer carbene complexes, which are molecules containing two different metal atoms. These intermediates will enable shape-selective control of the reactions.