Mixed Hydrogen-Bonding Flavin Catalysis for Asymmetric Transformations

描述（由申请人提供）：有机化合物中不对称性的催化生成是现代合成有机化学的主要焦点。虽然在过去的几十年里，沿着这些路线已经取得了沿着许多进展，但以光学纯形式产生任何给定立构中心的问题远未解决。金属介导的不对称催化已经创造了无数的小分子的对映选择性合成方法，但所涉及的金属可能是昂贵的，危险的，并且难以大规模去除。不对称有机催化提供了一个可持续的和非常有用的替代品，特别是在氢键催化领域。手性脲和硫脲氢键供体在催化许多不对称碳-碳键形成反应中显示出广泛的实用性，部分原因是它们结合和活化各种路易斯碱性和离子底物的能力。这种催化的一个未开发的用途是它在不对称氧化和还原反应中的应用。黄素蛋白是一类利用黄素辅因子进行氧化转化的酶。一种较少探索（与氢键催化相比）但令人惊讶地强大的有机催化竞技场涉及使用非酶结合的黄素来活化过氧化氢或肼以进行相应的氧化或还原反应。很少有方法将黄素催化应用于对映选择性反应。该提议试图将不对称氢键催化和黄素催化这两个概念联合收割机组合成混合催化体系，该混合催化体系能够在多种底物上实现对映选择性氧化和还原转化。硫脲或脲和黄素催化剂库将基于已建立的方法合成，并组合应用于不对称Baeyer-Villiger反应、缺电子烯烃的不对称环氧化和缺电子烯烃的不对称氢化。在所有提出的反应中，双氮和/或水是唯一的副产物。小分子疗法可以说是医学上对抗健康相关问题的最佳工具。因此，始终存在对快速、廉价和环境友好地生产潜在药物的需求。由于该提案寻求创造用于选择性合成小分子而没有危险副产物的新方法，因此它与公共卫生特别相关。

DESCRIPTION (provided by applicant): The catalytic generation of asymmetry in organic compounds is a major focus of modern synthetic organic chemistry. While many advances have been made along these lines in the past decades, the problem of creating any given stereocenter in optically pure form is far from being solved. Metal-mediated asymmetric catalysis has created countless methods for the enantioselective synthesis of small molecules, but the metals involved can be costly, hazardous, and difficult to remove on a large scale. Asymmetric organocatalysis provides a sustainable and highly useful alternative specifically in the realm of hydrogen-bonding catalysis. Chiral urea and thiourea hydrogen bond donors have shown broad utility in catalyzing a number of asymmetric carbon-carbon bond forming reactions, due in part to their ability to bind and activate a variety of Lewis-basic and ionic substrates. An underdeveloped use of such catalysis is its application to asymmetric oxidation and reduction reactions. Flavoproteins are a diverse class of enzymes that utilize a flavin cofactor to perform oxidative transformations. A less explored (as compared to hydrogen-bonding catalysis) but surprisingly powerful arena of organocatalysis involves using non-enzyme-bound flavins to activate hydrogen peroxide or hydrazine for respective oxidation or reduction reactions. Few methods have applied flavin catalysis to enantioselective reactions. This proposal seeks to combine the two concepts of asymmetric hydrogen-bonding catalysis and flavin catalysis into a hybrid catalytic system that would be capable of achieving enantioselective oxidative and reductive transformations on a wide variety of substrates. A library of thiourea or urea and flavin catalysts will be synthesized based on established methods and combined in application to the asymmetric Baeyer-Villiger reaction, the asymmetric epoxidation of electron-deficient olefins, and the asymmetric hydrogenation of electron-deficient olefins. In all of the proposed reactions dinitrogen and/or water are the sole byproducts. Small-molecule therapeutics are arguably medicine's best tools for combating health-related problems. Therefore, there is an ever-present need for the rapid, inexpensive, and environmentally friendly production of potential drugs. Since this proposal seeks to create new methods for the selective synthesis of small molecules with no hazardous byproducts it is of particular relevance to public health.