New Reactivity Pathways Using Pincer Ligands with Central Lewis Acidic Sites

在化学系化学合成计划的资助下，德克萨斯农工大学(TAMU)化学系的奥列格·奥泽罗夫教授将选择性地修饰含氮有机分子中的化学键，即含氮杂环。在许多药物和农用化学品的工业生产中，经常需要高效地制备和进一步修饰含氮杂环。然而，目前用于这些转化的过程往往效率低下，并且不能准确地针对必须操纵的化学键。为了纠正这一问题，构建了含有与硼或铝原子键合的金属原子的骨架。硼或铝原子可以捕获一个氮原子，并将含氮杂环保持在一个非常受控制的几何形状中，这使得金属原子能够激活特定的化学键。这允许对含氮杂环进行精确控制。该项目涉及一个合作者网络，包括伊萨卡学院的安娜·拉森教授和里士满大学的迈尔斯·约翰逊助理教授，他们都是主要是本科院校的教员。该项目还旨在通过研究生招生工作和与当地中学的接触，增加来自代表性不足群体的学生的参与。该项目的主题涉及协同使用与过渡金属键合并并入钳型配体的硼基或铝基中心的刘易斯酸性。它利用硼基或铝基单元的能力来捕获氮基底物中的氮基。这就定位了过渡金属来激活特定的C-H键，这在拓扑上与传统的C-H激活方法不同。为了开发新的配体文库，1，2-吡咯二基将被用作合成含有硼基或铝基的钳型配体的关键构件。利用这些配体，将制备Rh、Ir和Ru的配合物，并研究它们激活C-H键的能力。探讨了B或Al在有机碎片往返于过渡金属中的作用及其在C-H活化过程中的作用。最后，对氮杂环丙烷及其相关底物的催化功能化进行了研究。这项拟议的研究涉及与PUI的两位合作者拉森博士(伊萨卡学院)和约翰逊博士(里士满大学)的互动，并将通过TAMU研究生导师与伊萨卡学院和里士满大学本科生之间的密切联系进行。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Synthesis Program in the Chemistry Division, Professor Oleg Ozerov at the Department of Chemistry at Texas A&M University (TAMU) will selectively modify chemical bonds in nitrogen-containing organic molecules, called nitrogen-containing heterocycles. The efficient preparation and further modification of the nitrogen-containing heterocycles frequently is necessary in the industrial production of many pharmaceuticals and agrochemicals. However, the processes that are presently used for these transformations are often inefficient and do not exactly target the chemical bonds that must be manipulated. To rectify this problem, frameworks containing metal atoms bonded to boron or aluminum atoms are constructed. The boron or aluminum atoms can capture a nitrogen atom and hold the nitrogen-containing heterocycle in a very controlled geometry that allows the metal atom to activate specific chemical bonds. This permits precise control of the nitrogen-containing heterocycle. The project involves a network of collaborators, including Professor Anna Larsen at Ithaca College and Assistant Professor Miles Johnson at the University of Richmond, both faculty at primarily undergraduate institutions. The project also aims to increase the participation of students from underrepresented groups through graduate student recruitment efforts and outreach with the local secondary schools.The theme of this project involves the synergistic use of the Lewis acidity of boryl or aluminyl sites bonded to transition metals and incorporated into pincer type ligands. It exploits the ability of boryl or an aluminyl units to capture the nitrogenous group in an azine substrate. This positions the transition metal to activate a specific C-H bond, which is topologically distinct from traditional C-H activation approaches. To develop a library of new ligands, 1,2-pyrrolediyl will be utilized as a key building block in the synthesis of pincer type ligands that contain the boryl or aluminyl moieties. Using these ligands, rhodium, iridium, and ruthenium complexes will be prepared and their ability to activate C-H bonds will be investigated. The mechanistic roles of B or Al in shuttling organic fragments to and from the transition metal and their involvement in the C-H activation process will be probed. Finally, the catalytic functionalization of azines and related substrates will be developed. The proposed research involves interactions with two PUI collaborators, Dr. Larsen (Ithaca College) and Dr. Johnson (U. of Richmond), and will proceed via close connections between TAMU graduate student mentors and Ithaca College and University of Richmond undergraduates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.