Synthetic and Mechanistic Studies of Organometalloids

有机合成计划将为威斯康星大学麦迪逊分校化学系的汉斯·J·赖克博士提供支持。这项工作将通过揭示一些中间体的性质并应用这些知识来开发更大的合成控制，从而开发主要基团的合成潜力。现代农业和医学所使用的复杂分子的合成需要高度复杂的合成方法。这项研究主要集中在有机金属化学和有机金属化学的几个领域。具体地说，描述了旨在阐明有机锂试剂的一些重要的歧化反应--金属-卤素交换和有机锡化合物的金属转移反应--的机理的实验。由于这些反应在制备有机化学中得到了广泛的应用，从机理上理解它们是很重要的。所描述的实验将阐明ATE络合物在有机锂试剂化学中所起的作用，并将确定这些络合物本身是否是有用的碳负离子供体。将研究一种确定非立体形成中心(二价碲)亲核攻击几何形状的新技术。一项探索性的研究将确定动态核磁共振技术是否也可以用于研究烯醇化反应，该技术提供了关于苯基锂和碘苯之间简并的Li/I交换机理的详细信息。第二部分是手性亲电硒化试剂的设计。该试剂旨在利用高价有机硒物种的几何构型，这些物种被认为是R-Se+物种与烯烃亲电加成的中间体。如果该方法成功，将提供一种将烯烃不对称氧化成非外消旋的烯丙醇或内酯的方法。第三部分涉及继续正在进行的研究，以调查使用硅酮作为羰基叶立德前体的可能性。

The Organic Synthesis Program will provide support to Dr. Hans J. Reich in the Department of Chemistry at the University of Wisconsin in Madison. The work will develop the synthetic potential of the main group by unraveling the nature of some of the intermediates and applying this knowledge to develop greater synthetic control. The synthesis of the complex molecules utilized by modern agriculture and medicine requires highly sophisticated synthetic methodology. This research is in several areas of main group organometalloid and organometallic chemistry. Specifically, experiments aimed at elucidating the mechanism of some important metathesis reactions of organolithium reagents, the metal-halogen exchange and the transmetallation reaction of organotin compounds, are described. Since these reactions are widely used in preparative organic chemistry it is important to understand them mechanistically. The experiments described will clarify the role that ate complexes play in the chemistry of organolithium reagents, and will establish whether the complexes themselves are useful carbanion donors. A new technique for determining geometry of nucleophilic attack at non-stereogenic centers (divalent tellurium) will be examined. An exploratory study will establish whether a dynamic NMR technique which has provided detailed information concerning the mechanism of the degenerate Li/I exchange between phenyllithium and iodobenzene, can also be used to study enolate reactions. The second part concerns the design of a chiral electrophilic selenenylation agent. The reagent is designed to utilize the geometry of hypervalent organoselenium species thought to be intermediates in the electrophilic addition of R-Se+ species to olefins. The process, if successful, would provide a method for asymmetric oxidation of olefins to nonracemic allyl alcohols or lactones. A third part involves the continuation of ongoing research to investigate the potential of using silyl ketones as precursors to carbonyl ylides.