Exploitation of strongly pi-donating Ylidic substituents

强 pi-donating ylidic 取代基的开发

• 批准号: 386618-2010
• 负责人: Dyker, CAdam
• 金额: $ 2.55万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=572996
• 关键词: Exploitation; strongly; pi; donating; Ylidic

Replacing one or more hydrogen atoms in a molecule by another atom or group of atoms, known as a substituent, will result in a new molecule with altered properties relative to the parent structure. The influence of the substituent can be very dramatic and offers the opportunity to access important chemical properties from even simple frameworks. As an example, the substitution of the four hydrogen atoms in ethene, an inert gaseous molecule, with four nitrogen-based substituents (amino groups) gives rise to an air-sensitive ethene derivative that can be used as a homogeneous reducing agent in chemical synthesis. In another case, it was discovered two decades ago that replacing hydrogen atoms in methylene (the parent "carbene" with a fleeting lifetime as a reactive intermediate) with amino substituents leads to bottle-able(!) solids that have now become ubiquitous in many areas of chemistry. These, and many other achievements, result from the superb "pi-donating" effects of the amino substituents. Recent results, however, have demonstrated that so-called "ylidic" substituents surpass classical amino functionalities as pi-donors. The targeted exploitation of this fact will open up many new avenues of fundamental and applied chemistry, and is the central theme of the proposed research program. Specific goals of this research include: 1) the preparation of the most powerful organic reducing agents as selective and homogeneous alternatives to heterogeneous metals. The absence of metallic by-products is of particular value for pharmaceutical syntheses; 2) the stabilization of as-of-yet elusive reactive intermediates. These compounds are invoked as transient molecules in many synthetic pathways and their stabilization will provide important fundamental knowledge, but also allow for them to be used in other applications (just as for carbenes); 3) the preparation of new families of compounds (ligands) capable of donating above-average amounts of electron density to transition metals. These ligands will subsequently be used in transition metal catalysis, with the goal of discovering highly active catalysts for new or improved synthetic methodologies relevant to natural products, and materials science.

用另一个原子或原子团（称为取代基）替换分子中的一个或多个氢原子，将产生相对于母体结构具有改变的特性的新分子。取代基的影响可能非常巨大，并且提供了从简单的框架中获取重要化学性质的机会。例如，惰性气体分子乙烯中的四个氢原子被四个氮基取代基（氨基）取代，产生了对空气敏感的乙烯衍生物，可用作化学合成中的均相还原剂。在另一种情况下，二十年前发现用氨基取代基取代亚甲基（母体“卡宾”，作为反应中间体，寿命短暂）中的氢原子会产生可装瓶（！）的固体，现在这种固体在许多国家都已普遍存在。化学领域。这些以及许多其他成就都是氨基取代基卓越的“π-捐赠”效应的结果。然而，最近的结果表明，所谓的“ylidic”取代基作为 pi 供体超越了经典的氨基官能团。对这一事实的有针对性的利用将为基础化学和应用化学开辟许多新的途径，并且是拟议研究计划的中心主题。这项研究的具体目标包括：1）制备最强大的有机还原剂，作为异质金属的选择性和均质替代品。不产生金属副产物对于药物合成具有特殊价值； 2）迄今为止难以捉摸的反应中间体的稳定化。这些化合物在许多合成途径中被用作瞬态分子，它们的稳定性将提供重要的基础知识，但也允许它们用于其他应用（就像卡宾一样）； 3）制备能够向过渡金属提供高于平均水平的电子密度的新化合物（配体）家族。这些配体随后将用于过渡金属催化，目的是为与天然产物和材料科学相关的新的或改进的合成方法发现高活性催化剂。