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中心自由基的前体。这些光晕衍生物在自由基反应中的作用已经在许多合成例子中得到证实，并且经常在化学文献中得到回顾。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，烷氧化物、胺、氰化物、烯醇酸酯等）的麻烦干预。为了克服这个固有的问题，我们开始寻找一种反应性的碘化烷基当量，它对普通的亲核攻击是稳定的。在此，我们希望报告ο-（ο-碘苯基）苯硫代衍生物在温和条件下具有各种官能团相容性，可以快速生成碳自由基。这种方法扩大了自由基化学的范围，因为使用巯基的多种亲核反应（硫代缩醛化、共轭加成、环氧化物开放等）可以很容易地与目前的自由基生成过程结合。除了ο-（ο-碘苯基）苯硫衍生物外，ο-[(E)-2-三甲基硅基-2-碘乙烯基]苯硫衍生物也被引入，作为生成碳中心自由基的有效前体，即使在某些亲核试剂存在的情况下；这为在温和条件下诱导有效的嵌合效应的结构要求提供了有用的信息。上述化学性质促使我们研究利用这种嵌合效应生成所需碳种的可能性。考虑到结构类型限制下的通用性和可用性，我们重点研究了ο-（ο-碘苯基）苯基硒基或碲烯基衍生物与市售烷基锂的组合使用，期望通过初始的锂卤素交换和随后的阴离子易位可以有效地制备各种烷基锂试剂。在与羰基化合物的原位俘获反应中，评价了其合成效用和局限性。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