Bimetallic Carbene Complexes as Reagents and Catalysts for Organic Synthesis

本研究涉及开发新方法，用于指导Fischer碳络合物的强大碳-碳键形成化学，以用于有机合成。它将重点讨论烯烃的环丙烷化和几个炔烃的加成/插入反应。关键的中间体是杂双金属费舍尔卡宾配合物，其中一个缺电子的金属中心连接在金属羰基部分的杂原子上。由于缺乏电子的性质和快速的配体取代化学，刘易斯酸性金属取代基将在这些双金属体系的化学中发挥四方面的作用：(1)作为模板，将带有配体“手柄”的底物分子附着在其上，以实现新的和有用的非对映选择性；(2)作为手性助剂的附着位点，实现不对称诱导；(3)作为分子内亲核反应性的来源，允许稳定的菲舍尔卡贝烯被杂原子位移激活；(4)作为在温和条件下再生卡贝烯部分的手段，允许在催化条件下进行目标反应。有了这个奖项，化学分部的合成有机项目将支持弗吉尼亚大学化学系的M. G. Finn博士的研究。这项研究是在合成方法学领域，将开发指导碳-碳键形成的新方法，这是有机化学中最重要的一类反应之一。该过程中的关键中间体是杂双金属费雪卡宾配合物，它是含有两个不同金属原子的分子。这些中间体将使反应的形状选择控制成为可能。

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.