Design of Metal Artificial Enzymes and the Application to Fine Organic Synthesis

烷基卤化物，特别是碘化物和溴化物，在有机合成中经常被用作生成各种碳心自由基的前体。这些卤化物衍生物在自由基反应中的有效性已经在许多合成例子中得到了证明，并经常在化学文献中得到综述。然而，使用这种反应性的烷基卤化物进行自由基反应有不可避免的缺点，这主要是由于内部和/或外部亲核试剂(例如，烷氧基、胺、氰化物、烯醇酸盐等)的麻烦干预。为了克服这个固有的问题，我们开始寻找一种对普通亲核攻击稳定的反应性烷基碘等效物。在此，我们希望报告ο-(ο-碘苯基)苯硫基衍生物在温和的条件下具有多种官能团相容的高效快速生成碳自由基的能力。这种方法扩大了自由基化学的范围，因为各种亲核试剂t…更多的硫代缩醛、共轭加成、环氧化物开环等。使用芳硫醇可以很容易地与目前的自由基产生过程相结合。ο-[(E)-2-Trimethylsilyl-2-iodovinyl]phenylthio衍生物除了ο-(ο-碘苯基)苯硫基衍生物外，还被引入作为生成碳中心自由基的有效前体，即使在某些亲核试剂的存在下也是如此；这为在温和的条件下诱导有效的锚定效应提供了有用的结构要求。上述化学使我们研究了通过利用这种锚定效应来产生所需碳负离子物种的可能性。考虑到化合物的通用性和可用性，同时考虑到结构类型的限制，我们重点介绍了ο-(ο-碘苯基苯基亚硒基或碲基衍生物与商业上可用的烷基锂化合物的联合使用，期望通过初始Li-卤素交换和随后的阴离子转移来有效地制备各种烷基锂试剂。在与羰基化合物的原位捕集反应中，评价了其合成的实用性和局限性。较少

Alkyl halides, especially iodides and bromides, are frequently utilized as precursors to generate various carbon-centered radicals in organic synthesis. The usefulness of these halo derivatives in radical reactions has been demonstrated in numerous synthetic examples and often reviewed in the chemical literature. There is, however, inevitable drawback to the use of such reactive alkyl halides for radical reactions, and this is mainly due to the troublesome intervention of internal and/or external nucleophiles (e.g., alkoxides, amines, cyanide, enolates, etc.). To overcome this intrinsic problem, we initiated the search for a reactive alkyl iodide equivalent which is stable for ordinary nucleophilic attack. Herein we wish to report that ο-(ο-iodophenyl)phenylthio derivatives are highly effective with various functional group compatibility for rapid generation of carbon radicals under mild conditions. This approach expands the scope of radical chemistry, since a variety of nucleophilic t … More hiolations (thioacetalization, conjugate addition, epoxide opening, etc.) using arythiol can be readily combined with the present radical generation process. In addition to ο-(ο-iodophenyl)phenylthio derivatives, ο-[(E)-2-Trimethylsilyl-2-iodovinyl]phenylthio derivatives have been also introduced as effective precursors for the generation of carbon centered radicals even in the presence of certain nucleophiles ; this provides useful information about the structural requirement for inducing an efficient anchimeric effect under mild conditions.The above mentioned chemistry led us to investigate the possibility of generating desired carbanion species by the utilization of such anchimeric effect. Taking both the versatility and the availability with the limitation of structural types into account, we focused on the combined use of ο-(ο-iodophenyl)phenylselenenyl or tellurenyl derivatives and commercially available alkyllithiums, expecting that various alkyllithium reagents could be efficiently prepared through the initial Li-halogen exchange and subsequent translocation of the resulting anion. The synthetic utility as well as the limitation were evaluated in the in situ trapping reaction with carbonyl compounds. Less