New, Rational Synthetic Transformations Based on the Oxidation Potentials as Universal Reactivity Indices

我们已经研究了新的合成转换的基础上合理的设计和预测的反应物的反应性，使用的氧化电位作为通用的反应性指数。我们开发了一种新型高效的电动辅助设备; 2-吡啶基甲硅烷基取代的硫醚的氧化电位比未取代的硫醚的氧化电位低得多，而2-吡啶基硅基的作用可以通过吡啶基对硫衍生自由基阳离子的分子内参与来解释，其由起始衬底的单电子氧化产生。2-吡啶基硅基对二价有机硫化合物氧化电位的降低作用强于一般的有机硅基，说明2-吡啶基硅基的碱性强于吡啶基，这是由于吡啶基氮原子的n-轨道与C-Si键的σ-轨道相互作用的结果。因此，2-吡啶基硅基有望在金属催化反应中作为强有力的分子内配体。在内部，我们已经成功地开发了各种有机金属介导的合成反应，包括硅氢加成，Heck型反应，Stille型反应，碳镁化和硅甲基的去质子化。

We have investigated new synthetic transformations based on rational design and prediction of the reactivity of reactants using the oxidation potentials as universal reactivity indices. We have developed a new and highly effective electro-auxiliary ; 2-pyridylsilyl group, which can be also used for removable intramolecular ligand for metal-mediated and catalyzed reactions.The oxidation potential of the α-2-pyridylsilyl-substituted sulfide is considerably lower than that of the non-substituted one, and the effect of 2-pyridylsilyl group can be explained by the intramolecular participation of the pyridyl group to the sulfur-derived radical cation spesies, which are generated by single electron oxidation of the starting substrate. This participation effect is also supported by the fact that 2-pyridylsilyl group possesses stronger effect than ordinary organosilyl group to decrease the oxidation potentials of divalent organosulfur compounds.The results above suggest that the basicity of 2-pyridylsilyl group is stronger than that of pyridine because of the existence of the interaction of the n-orbital of the pyridyl nitrogen and the σ-orbital of the C-Si bond. Therefore, 2-pyridylsilyl group is expected to serve as a powerful intramolecular ligand in metal-mediated and catalyzed reactions. Inside, we have succeeded in developing various organometallic-mediate synthetic reactions, including the hydrosilylation, the Heck-type reaction, the Stille-type reaction, the carbomagnesiation, and the deprotonation of silylmethyl groups.