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Metal-Free Functionalization of Electron Rich Aromatic Systems: ortho-Quinone Methides, Aza-ortho-Xylylenes, and N,N-Dialkylaniline N-Oxides in Synthesis

富电子芳香族体系的无金属官能化：邻醌甲基化物、氮杂邻二甲苯和 N,N-二烷基苯胺 N-氧化物的合成

基本信息

批准号：
1664954
负责人：
William Chain
金额：
$ 33.5万
依托单位：
University of Delaware
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-08-01 至 2020-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1664954&HistoricalAwards=false
关键词：
Metal Free Functionalization Electron Rich

项目摘要

The Chemical Synthesis Program of the Chemistry Division supports the project by Professor William Chain. Professor Chain is a faculty member in the Department of Chemistry & Biochemistry at the University of Delaware. He is developing new classes of reactions that that are facilitated by reversing the normal polarity and hence reactivity of molecules. Reversing the polarity means that molecules that normally behave as if they are negatively charged behave as if they are positively charged. The change facilitates the formation of a wide array of new carbon-carbon, carbon-oxygen, carbon-nitrogen, and carbon-sulfur bonds that lie at the heart of chemical structures that serve many purposes in industrial, chemical, and medical applications. Professor Chain's research group provides the highest level of education and training for students at all ages. It also offers opportunities for students typically underrepresented in science. Professor Chain is actively engaged in outreach activities in local elementary, middle, and high schools to promote science education and engagement of students in science disciplines. These activities include summer research internships in Professor Chain's laboratory for promising high school seniors. These internships encourage student interest in university studies and careers in the sciences. An array of aromatic substitution reactions have been described since the seminal work of Charles Friedel and James Crafts in the mid to late 1800's. Despite this body of work, there are still limitations in electron-rich settings; functionalization of electron-rich aromatic systems can be controlled by virtue of a temporary inversion of reactivity. Generating and engaging highly reactive intermediates in a controlled and predictable manner by an umpolung strategy is a critical tool set in organic synthesis. Synthetic strategies in this regard are the manipulation of latent aromatic compounds and/or the temporary engagement of heteroatom-bound electron pairs and harnessing these energetic structures to form congested carbon-carbon and carbon-heteroatom bonds. This award explores two reactivity manifolds available to phenols and anilines. In the first reactivity manifold, silyl-protected phenols and anilines are converted to ortho-quinone methides (QOMs) and aza-ortho-xylylenes (AOXs). These protected species are mixed with silyl enol ethers or silyl ketene acetals to release both the electrophilic and nucleophilic participants in conjugate addition reactions by treatment with easily dispensed and handled fluoride sources. In the second reactivity manifold, anilines are oxidized to the corresponding N-oxides, which facilitates an array of bond formations that take advantage of the excision of the weak N-O bond. By virtue of these mild reaction conditions, the scope and capability of umpolung reactions with electron rich aromatic rings is expanded. The educational plan includes outreach to local elementary, middle, and high schools with integration of high school students into the research program in as research interns.

化学系的化学合成计划支持William Chain教授的项目。 Chain教授是特拉华州大学化学生物化学系的教员。他正在开发新的反应类别，这些反应通过逆转分子的正常极性和反应性来促进。反转极性意味着通常表现为带负电荷的分子表现为带正电荷。这种变化促进了一系列新的碳-碳、碳-氧、碳-氮和碳-硫键的形成，这些键位于化学结构的核心，在工业、化学和医学应用中具有多种用途。 Chain教授的研究小组为所有年龄段的学生提供最高水平的教育和培训。它还为通常在科学领域代表性不足的学生提供了机会。 Chain教授积极参与当地小学，初中和高中的外展活动，以促进科学教育和学生对科学学科的参与。这些活动包括在Chain教授的实验室为有前途的高中毕业生提供暑期研究实习。这些实习鼓励学生对大学学习和科学职业的兴趣。自从Charles Friedel和James Crafts在19世纪中后期的开创性工作以来，已经描述了一系列芳香族取代反应。尽管有这样的工作，但在富电子环境中仍然存在限制;富电子芳族体系的官能化可以通过反应性的暂时反转来控制。在有机合成中，通过一种可控制和可预测的方式，通过一个umpolung策略生成和接合高活性中间体是一个关键的工具集。在这方面的合成策略是操纵潜在的芳香族化合物和/或杂原子结合的电子对的临时接合，并利用这些高能结构形成密集的碳-碳和碳-杂原子键。该奖项探讨了两个反应歧管可用于苯酚和苯胺。在第一反应性歧管中，甲硅烷基保护的苯酚和苯胺被转化为邻醌甲基化物（QOM）和氮杂邻二甲苯（AOX）。这些受保护的物质与甲硅烷基烯醇醚或甲硅烷基烯酮缩醛混合，通过用容易分配和处理的氟化物源处理，在共轭加成反应中释放亲电和亲核参与物。在第二反应性歧管中，苯胺被氧化成相应的N-氧化物，这有利于利用弱N-O键的切除形成一系列键。由于这些温和的反应条件，扩大了富电子芳环的极化反应的范围和能力。教育计划包括推广到当地小学，初中和高中，高中学生融入研究计划作为研究实习生。