Development of New Radical Coupling Reactions at Carbon-Heteroatom Multiple Bonds

自由基在碳-碳多键上形成碳-碳键，如烯烃和烯烃，因其用途广泛而被广泛应用于有机合成中。然而，关于碳-杂原子多键(如羰基和亚胺)上碳-碳键的形成知之甚少。本研究的目的是在我们最新研究的硅碲化物和碳杂原子多键反应的基础上，发展一种新的碳杂原子多键合成自由基反应。该反应在温和的热条件下进行，得到了具有高立体选择性的相应的含乙烯基碲的E-烯丙基醇。此外，自由基和阴离子介导的乙烯基碲化物的转化对多取代烯烃的立体选择性合成具有很高的应用价值。因此，偶联反应为合成具有特定几何构型的多取代烯烃提供了一种有效的策略。我们还开发了一种新的亚胺与异腈的偶联反应，该反应由一类新的硅基碲化物试剂三乙氧基硅基苯基碲化物催化，合成了α-硅胺甲基亚胺基碲化物。在偶联产物中碳-碲键的转化提供了α-氨基酸衍生物以很好的到很好的产率。上述自由基偶联反应以及随后的合成转化对羰基、亚胺、炔烃和异腈的取代不敏感。因此，我们阐明了目前的方法适用于小分子文库的组合合成。

Radical mediated carbon-carbon bond formation at carbon-carbon multiple bonds, such as alkene and alkyne, has been widely utilized in organic synthesis due to its versatilities. However, little is known for the carbon-carbon bond formation at carbon-heteroatom multiple bonds, such as carbonyls and imines. This research was aimed to develop a new synthetic radical reaction at carbon-heteroatom multiple bonds based on the reaction of silyltellurides and carbon-heteroatom multiple bonds, which we have recently developed.A new coupling reaction of carbonyl compounds with alkynes mediated by trimethylsilylphenyltelluride has been developed. The reaction proceeded under mild thermal conditions to give the corresponding E-allylic alcohols bearing vinyltelluride group with high stereoselectivity. Furthermore, radical- and anion-mediated transformations of the vinyltellurides were highly useful for the stereoselective synthesis of multi-substituted alkenes. Therefore, the coupling reaction followed by the transformations provides a powerful strategy for the synthesis of multi-substituted alkenes with defined geometry.We have also developed a new coupling reaction of imines with isonitriles mediated by triethoxysilylphenyltelluride, a new class of silyltelluride reagent, to give α-silylaminomethylimidoyltellurides. The transformation of the carbon- tellurium bond in the coupling products afforded α-amino acid derivatives in good to excellent yields.The above mentioned radical coupling reactions as well as the subsequent synthetic transformations are insensitive to the substitutions of carbonyls, imines, alkynes, and isonitriles. Therefore, we clarified that the current method is suitable for the combinatorial synthesis of small molecule libraries.