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

我们研究了基于合理设计和以氧化势作为通用反应性指标预测反应物反应性的新的合成转化。我们开发了一种新型高效电辅；2-吡啶烷基，也可用于金属介导和催化反应的可移动分子内配体。α-2-吡啶基基取代的硫化物的氧化电位明显低于未取代的硫化物，2-吡啶基的作用可以用吡啶基参与起始底物单电子氧化产生的硫衍生自由基阳离子来解释。2-吡啶硅基对二价有机硫化合物的氧化电位的降低作用比普通有机硅基更强，这也支持了这种参与效应。以上结果表明，2-吡啶基硅基的碱性比吡啶强，这是由于吡啶基氮的n轨道与C-Si键的σ轨道存在相互作用。因此，2-吡啶基硅基有望在金属介导和催化反应中作为一种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，包括硅氢化反应、heck型反应、stille型反应、碳镁化反应和硅基甲基的去质子化反应。

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.