Asymmetric Synthesis with Chiral Heteroalkyl Radicals

在有机和大分子化学项目的支持下，凯斯西储大学化学系的Philip P. Garner教授正在研究利用手性杂烷基自由基进行不对称合成。加纳教授正在开发一种通用的、迭代的聚合物支持的多元醇自由基合成方法，并将吡喃烷手性助剂的使用扩展到合成有用的闭壳过程中。将定义这种迭代方法的最佳树脂连接剂策略，并开发用于定量聚合物支撑反应的技术。还将探讨减少每次迭代自由基同源序列所需的步骤数和减少手性辅助物的结构的方法。吡啶类手性助剂将应用于各种有用的闭壳过程。协调的环加成，烯丙基硼/烯醇酯烷基化，串联不对称硼氢化/铃木偶联序列将被检查，在溶液和聚合物载体上。虽然有机反应传统上是在溶液中进行的，允许反应物紧密混合，但发现反应物或试剂与不溶性“载体”相连的反应有许多优点。例如，如果用过的试剂附着在这样的载体上，它可以很容易地从反应混合物中除去，而如果附着所需的化合物，杂质可以很容易地被洗掉。凯斯西储大学化学系的Philip P. Garner教授因其在这一领域的努力而得到了有机和大分子化学项目的支持。加纳教授正在利用含有未配对电子的化合物（“自由基”）的反应化学，寻找控制其反应活性的方法，以便对其反应产物进行精确的几何控制。

With the support of the Organic and Macromolecular Chemistry Program, Professor Philip P. Garner, of the Department of Chemistry at Case Western Reserve University, is studying asymmetric synthesis using chiral heteroalkyl radicals. Professor Garner is both developing a general, iterative polymer-supported radical synthesis of polyols and extending the use of pyranosidic chiral auxiliaries to synthetically useful closed-shell processes. The optimal resin-linker strategy for this iterative approach will be defined and techniques developed for the quantification of polymer-supported reactions. Methods for reducing the number of steps required for each iteration of the radical homologation sequence and paring down the structure of the chiral auxiliary will also be explored. Pyranosidic chiral auxiliaries will be applied to a variety of useful closed-shell processes. Concerted cycloadditions, allylboron/enolate alkylations, and a tandem asymmetric hydroboration/Suzuki coupling sequence will be examined, both in solution and on polymer supports.While organic reactions have traditionally been carried out in solution, allowing intimate mixing of reactants, there are many advantages to finding reactions in which either a reactant or a reagent is linked to an insoluble "support." If a spent reagent is attached to such a support, for example, it may be easily removed from the reaction mixture, while if a desired compound is attached, impurities may be easily washed away. Professor Philip P. Garner, of the Department of Chemistry at Case Western Reserve University, is supported by the Organic and Macromolecular Chemistry Program for his efforts in this area. Professor Garner is harnessing the reaction chemistry of compounds containing an unpaired electron ("radicals"), finding ways to control their reactivity so as to allow precise geometrical control over the products of their reactions.