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Highly Selective Carbon-carbon Bond Cleacage by Super-protic Directory Groups

超质子目录群的高选择性碳-碳键断裂

基本信息

批准号：
61470087
负责人：
ITOH Kenji
金额：
$ 3.39万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The group 14 organometallic groups have been known to stabilize a carbocations locating at their <beta>. In this project, several extentions of this concept were investigated for seceloping highly selective cleavage processes of a -bond, such as carbon-carbon bonds unser moderate consitions Several<beta>-tri- methylsilylketoxime acetates were found to induce the highly regio-and strtro- specific Beckmann fragmentation to yield the corresponding alkeyl cyanides by an electrophilic activation with trimethylsilyl triflate. This methodology was much superior to the more common activation of a Si-C bond with flurides. This new fragmentation is particularly useful to the stereospecific fromation of olefins as exemplified by synthesis of several insect pheromones. Streroselective introduction of both metallyl function and the carbon moiety was achieved by the conjugate addition of alkenones in one-pot.Alternatively, the organostannyl substituted ketoximes were found to cleave their <beta>-carbon-carbon bonds by oxidative activation with lead tetraacetate. This new process was also highly regio-and stereospecific to furnish alkenyl nitrile oxide intermediates, Which undergo intranolecular dipolar cycloadditions sponta- neously to give <DELTA>-isoxazolines. The super-protic natureof group 14 organo- metallyl groups was also applied to the selective decartboxylation of <beta>-metallyl- carboxylic acids and to the pyrazoline formation of tin-substituted hydrazines.Modification of the cationic center to carbon to a transition-metal, an allylbromoruthenium(IV) moiety, resulted in an unprecedented silver fluoride activation of a carbon-silicon bond by way of a new methyl group migration from silicon to ruthenium atoms.

已知第14族有机金属基团稳定位于其上的碳阳离子<beta>。在本项目中，我们研究了这一概念的几种扩展，以在中等条件下产生高选择性的α-键断裂过程，如碳-碳键<beta>。发现几种三甲基甲硅烷基酮肟乙酸酯通过三甲基甲硅烷基三氟甲磺酸酯的亲电活化诱导高度区域和结构特异性的贝克曼断裂，产生相应的烷基氰化物。这种方法比更常见的用氟化物活化Si-C键要优越得多上级。这种新的断裂特别适用于烯烃的立体专一性形成，例如几种昆虫信息素的合成。通过一锅法共轭加成实现了金属烯丙基官能团和碳部分的立体选择性引入，或者，发现有机锡烷基取代的酮肟<beta>通过四乙酸铅的氧化活化裂解它们的-碳-碳键。该新方法还具有高度的区域和立体专一性，可得到烯基腈氧化物中间体，其可自发地进行分子内偶极环加成反应，生成<DELTA>-异恶唑啉。超质子性质的第14族有机金属烯丙基也适用于选择性脱羧的<beta>-metallyl-羧酸和吡唑啉形成的锡取代的hydrazines.Modification的阳离子中心的碳过渡金属，烯丙基溴钌（IV）部分，导致了前所未有的银氟化活化的碳-硅键的方式，一个新的甲基迁移从硅到钌原子。