Organic Synthesis Using Electroauxiliaries

我们提出了电助剂的新概念，作为电子转移驱动反应的有用工具。电助剂激活反应物分子以促进电子传递过程，并控制由此产生的活性物种的化学过程以选择性地得到所需的产物。我们发现硅、锡和硫是用于杂原子化合物氧化的良好的电助剂。电助剂的概念对于杂原子化合物的氧化碳-碳键的形成是有用的。一些以锡和硫为电助剂的电氧化碳-碳键的形成反应也被发现是有机化合物的位置选择性转化，因为我们可以很容易地利用分子上不同位置的电助剂的氧化还原电位的差异来区分它们。我们还研究了电助剂的作用机理。在硅和锡的情况下，碳-金属西格玛轨道与杂原子的非键孔道的相互作用加速了电子的转移，从而提高了HOMO能级。然而，在硫的情况下，没有观察到这种相互作用，发现电子转移主要发生在硫原子上。

We propose a new concept of electroauxiliary as a useful tool in electron transfer-driven reactions. Electroauxiliaries activate reactant molecules to facilitate the electron transfer process and also control the chemical process of thus generated reactive species to give desired products selectively.We have found that silicon, tin, and sulfur serve as excellent electroauxiliaries for the oxidation of heteroatom compounds. The concept of electroauxiliary was found to be useful for oxidative carbon-carbon bond formation of heteroatom compounds. Several electrooxidative carbon-carbon bond formation reactions using tin and sulfur as electroauxiliaries have been developed.This concept was also found to be site-selective transformation of organic compounds because we can easily distinguish between electroauxiliaries at different sites of molecule using the difference of their redox potential.We also investigated the mechanism of the action of electroauxiliaries. In the case of silicon and tin, the electron transfer is accelerated by the interaction of the carbon-metal sigma orbital with the nonbonding porbital of the heteroatom which raises the HOMO level. In the case of sulfur, however, such interaction was not observed and the electron transfer was found to take place mainly from the sulfur atom.