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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=550518
• 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.

用另一个原子或一组原子（称为取代基）代替一个或多个分子中的氢原子，将导致相对于母体结构，具有改变性质的新分子。取代基的影响可能非常戏剧化，并提供了从简单框架甚至从简单框架中获取重要化学特性的机会。例如，用四个基于氮的取代基（氨基组）取代了乙烯中的四个氢原子，乙烯气态分子（氨基组）产生了空气敏感的乙烯衍生物，可以用作化学合成中的均质还原剂。在另一种情况下，在二十年前发现，用氨基取代基替换甲基中的氢原子（父母的“卡宾”，其短暂的寿命为反应性中间体）会导致在许多化学区域中无处不在的瓶装（！）固体。这些以及许多其他成就是由氨基取代基的极好的“ PI抑制”作用造成的。然而，最近的结果表明，所谓的“ YLIDIC”取代基超过经典的氨基功能作为PI-DONOR。对这一事实的有针对性的剥削将开辟许多基本和应用化学的新途径，并且是拟议研究计划的核心主题。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匀替代品。对于药物合成，缺乏金属副产品是特别值得的。 2）尚未达到尚未难以捉摸的反应性中间体的稳定。这些化合物在许多合成途径中被称为瞬态分子，它们的稳定化将提供重要的基本知识，但也允许它们用于其他应用中（就像碳纤维一样）。 3）制备能够捐赠高于平均值的电子密度向过渡金属捐赠的化合物（配体）。这些配体随后将用于过渡金属催化，目的是发现与天然产物和材料科学相关的新型或改进合成方法的高活性催化剂。