Surface-Mediated Electrophilic Additions

我们将研究硅胶和氧化铝对烯烃和炔烃的亲电加成反应的影响。为了更好地了解这一综合有用技术的机理特征，我们将系统地研究有机衬底与氧化铝和二氧化硅表面的相互作用，以及这些相互作用对衬底亲电加成的影响。将特别注意描述以前观察到的氧化铝和硅胶表面在中介亲电加成反应方面的差异，包括活性中心的空间需求的差异，以及开发在存在一个双键或三键的情况下实现选择性加成的技术。还将主要研究极性取代基对烯烃和炔的表面亲电加成反应的影响，特别注意取代基的指导作用，这些取代基可能导致氢卤化物、卤素、水、联苯和氰化氢的化学、区域或立体选择性加成。来自有机动力学项目的这笔资金支持北卡罗来纳大学保罗·J·克罗普教授的研究。Kropp博士的初步研究表明，氧化铝和硅胶的表面可以极大地影响各种化合物在双碳和三碳键上的加成。在本研究中，我们将研究氧化铝和硅胶介导的加成反应的细节。关于加成反应可能进行的过程，将研究连接到双碳碳键和三碳碳键的取代基的大小，以及这些多重键中的电子密度。这些研究结果将在有机分子的合成方法中有重要的应用。

A study will be made of the effect of silica gel- and alumina- mediated electrophilic addition reactions to alkenes and alkynes. In order to obtain a better understanding of the mechanistic features of this synthetically useful technique, a systematic study of the interaction of organic substrates with alumina and silica surfaces and the effects of those interactions on electrophilic additions to the substrates will be made. Particular attention will be given to delineating previously observed differences between alumina and silica gel surfaces in mediating electrophilic addition reactions, including differences in the steric demands of the active sites, and to developing techniques for effecting selective addition to one double or triple bond in the presence of another. A major study of the effects of polar substituents on surface-mediated electrophilic additions to alkenes and alkynes will also be undertaken, with special attention to directive effects of the substituents which may induce chemo-, regio-, or stereoselective additions of hydrohalides, halogens, water, hydrazoic acid, and hydrogen cyanide. %%% This grant from the Organic Dynamics Program supports the research of Professor Paul J. Kropp at the University of North Carolina. Preliminary studies by Dr. Kropp have shown that surfaces of alumina and silica gel can dramatically affect the addition of various compounds to double and triple carbon-carbon bonds. In the present study, the intimate details of alumina and silica gel mediated addition reactions will be investigated. The size of substituents bonded to double and triple carbon-carbon bonds, as well as the electron density in these multiple bonds, will be studied with regard to the possible courses that the addition reaction may take. The results of these studies will lead to important applications in synthetic methods for the preparation of organic molecules.