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，德克萨斯州农工大学（TAMU）化学系的Oleg Ozerov教授将选择性地修饰含氮有机分子中的化学键，称为含氮杂环。含氮杂环的有效制备和进一步修饰在许多药物和农用化学品的工业生产中经常是必需的。然而，目前用于这些转化的方法通常效率低下，并且不能精确地靶向必须操纵的化学键。为了纠正这个问题，构建了含有与硼或铝原子键合的金属原子的框架。硼或铝原子可以捕获氮原子并将含氮杂环保持在非常受控的几何形状中，这允许金属原子激活特定的化学键。这允许精确控制含氮杂环。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助理教授迈尔斯约翰逊，这两个教师主要是本科院校。该项目的另一个目的是通过招收研究生和与当地中学联系，增加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硼基或铝基的刘易斯酸性与过渡金属键合，并纳入钳型配体。它利用硼基或铝基单元捕获吖嗪底物中的含氮基团的能力。这将过渡金属定位成活化特定的C-H键，这在拓扑上不同于传统的C-H活化方法。为了开发新的配体库，1，2-吡咯二基将被用作合成含有硼基或铝基部分的钳型配体的关键构件。使用这些配体，铑，铱和钌配合物将制备和它们的能力，活化C-H键将进行研究。探讨了B或Al在有机碎片往返于过渡金属和它们在C-H活化过程中的作用机理。最后，将开发吖嗪和相关底物的催化官能化。拟议的研究涉及与两个PUI合作者，拉森博士（伊萨卡学院）和约翰逊博士（美国）的互动。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值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.