Novel oxidative functionalizations using earth-abundant transition metals

选择性好氧氧化的发展对化学工业至关重要，因为分子氧丰富，并且通过其还原为水提供了可持续的能源。一组特别重要的氧化反应是将氧原子或氮原子直接一步转移到失活的有机底物上，这产生通常用作燃料、溶剂和润滑剂或用作精细化学品和药物合成中的结构单元的分子。此外，这些直接的原子转移避免了浪费的保护基团策略的中介作用。然而，大多数现有方法使用有毒金属离子或浪费的氧化剂，这对于按比例放大的应用是不期望的。 这项研究计划的使命是开发新的策略，在环境友好的条件下，使用地球上丰富的金属离子将氧或氮转移到衬底上。这项研究将遵循两个主要方向。(1)：从生物含金属酶中获得灵感，这些酶在将氧气从空气转移到基质中时具有高效和选择性。(2)：开发用于氧和氮转移的新型试剂和催化剂，这些试剂和催化剂具有原子经济性，并使用地球上丰富的无毒金属离子，如铁和铜。我们提出了四个研究目标： - 目标1：以制备模拟酶的分子，并研究它们的结构和反应性，以开发更有效和更有选择性的催化剂。我们将特别关注参与环境中芳烃降解的反应。 - 目的二：制备金属自由基加合物模型，研究其与自由基的偶联反应。这种反应属于生物学，在合成策略中也很重要（例如，以数百万吨规模制造聚亚苯基醚或交叉偶联）。 - 目标3：利用含氮氧键的约束氧化还原活性配体促进氧转移。 - 目标四：发展一种新的含氮基团的转移方法，一步合成氨基酚结构单元。 该计划的共同主题是使用氧化还原活性配体，即具有自身氧化还原性质的配体。虽然与这些配体的金属配合物的结构是很好地理解，文献是稀缺的报告，其反应性。我们计划的新奇在于在氧化反应的背景下系统地使用这些配体，特别是在苯酚上，这些配体目前未被工业充分利用，因为没有好的方法将它们有效地和选择性地转化为有用的材料。因此，这项工作的预期成果将是理解和开发新的氧化方法，使工业界能够将未使用的化学品视为新的原料。

The development of selective aerobic oxidations is fundamentally important to the chemical industry due to the abundance of molecular oxygen and the sustainable source of energy provided by its reduction to water. A particularly important group of oxidation reactions is the direct, one-step transfer of an oxygen or nitrogen atom to an inactivated organic substrate, which generates molecules that are typically used as fuels, solvents and lubricants or as building blocks in the synthesis of fine chemicals and pharmaceuticals. Also, these direct atom transfers avoid the intermediacy of wasteful protecting-group strategies. However, most current methods employ toxic metal ions or wasteful oxidants, which is undesired for scaled-up applications. The mission of this research program is to develop new strategies for oxygen or nitrogen transfer to substrates using earth-abundant metal ions under conditions that are environmentally benign. This research will follow two main thrusts. (1): get inspiration from biological metal-containing enzymes that are efficient and selective at transferring oxygen from the air into substrates. (2): develop novel reagents and catalysts for oxygen and nitrogen transfers that are atom-economical and employ earth-abundant and non toxic metal ions such as iron and copper. We propose four research objectives: - Objective 1: to prepare molecules that mimic the enzymes and study their structure and reactivity to develop more efficient and more selective catalysts. We will particularly focus on reactions that are involved in the degradation of aromatics in the environment. - Objective 2: to prepare models of metal-radical adducts and study their coupling reactions with radical partners. Such reactions pertain to biology and are also important in synthetic strategies (for example the fabrication of polyphenylene ether at a multi-million ton scale or cross dehydrogenative couplings). - Objective 3: to employ constrained redox-active ligands containing an nitrogen-oxygen bond to facilitate oxygen transfer. - Objective 4: to develop a new methodology to transfer nitrogen-containing groups on phenols and open a one-step access to aminophenol building blocks. The common theme of this program is the use of redox-active ligands, i.e. ligands that possess their own redox properties. Although the structure of metal complexes with these ligands is well understood, the literature is scarce with reports of their reactivity. The novelty of our program stands in a systematic use of these ligands in the context of oxidation reactions, especially on phenols, which are currently underused by the industry because there is no good method to convert them efficiently and selectively to useful materials. Thus, the expected outcome of this work will be the understanding and development of new oxidative methods that will allow the industry to think of unused chemicals as new feedstock.