Asymmetric Construction of Benzylic Stereocenters via Reductive Copper Catalysis

 描述（由申请人提供）：开发更温和、更有效的复杂分子构建方法是有机合成研究的一个充满活力的领域。特别是，某些结构基序已经在有机化学中获得了特权地位，因为它们似乎普遍存在于生物活性分子中。例如，苄基碳立构中心是在药剂、农用化学品和天然产物分离物中发现的常见基序。在碳框架上提供的取代和官能度可以深刻地改变细胞膜渗透性、分子在生物环境中的半衰期和药物在人体内的效力。因此，非常需要为该基序产生广泛的催化平台。 氢化铜（I）化学的最新进展已经证明了这种催化平台在温和条件下用廉价的铜和硅烷来源生产非对映体富集和对映体富集分子的潜力。尽管如此，这种化学方法可以实现重大进展，走向其他不对称的方法。本提案中概述的两个具体目标详细说明了通过还原性铜催化催化的两种转化：对映选择性加氢芳基化和对映选择性苄基烷基化。提出的起始材料是苯乙烯，这是一类每年以数百万吨规模生产的分子，以及各种市售或易于生产的亲电源。 最后，将追求机械调查，以隔离在催化循环中的任何主管中间体，确定存在的任何铜（II）/铜（III）或自由基中间体，并开发立体化学模型。计算，动力学和光谱研究，反过来，将被应用到第二代配体框架合成和扩展这种不对称的方法，以其他类别的烯烃。

 DESCRIPTION (provided by applicant): The development of milder and more efficient methods towards complex molecule construction is a vibrant area of research within organic synthesis. In particular, certain structural motifs have achieved a privileged status within organi chemistry, due to their seemingly ubiquitous presence in bioactive molecules. For example, the benzylic carbon stereocenter is a common motif found in medicinal agents, agrochemicals, and natural product isolates. The substitution and functionality provided on the carbon framework can profoundly alter cell membrane permeability, half-life time of the molecule in a biological environment, and potency of a drug within the human body. Thus, the generation of a broad catalytic platform for this motif would be highly desirable. Recent advances in copper(I) hydride chemistry have demonstrated the potential of this catalytic platform for producing diastereoenriched and enantioenriched molecules under mild conditions with inexpensive sources of copper and silane. Still, significant advances could be achieved with this chemistry towards other asymmetric methodologies. Two specific aims outlined in this proposal detail two transformations that are catalyzed through reductive copper catalysis: enantioselective hydroarylation and enantioselective benzylic alkylation. The starting material proposed is styrene, a class of molecules produced on a millions of tons scale each year, and a variety of commercially available or easy-to-produce electrophilic sources. Lastly, mechanistic investigations will be pursued to isolate any competent intermediates in the catalytic cycle, identify the presence of any Cu(II)/Cu(III) or radical intermediates, and to develop a stereochemical model. Computational, kinetic, and spectroscopic investigations will, in turn, be applied to second-generation ligand framework synthesis and the expansion of this asymmetric methodology to other classes of olefins.