Development of Novel Radical Chemistry Utilizing the Heavy Group 15 Heteroatom Compounds

有机硒、碲化物、溴化物和碘化物等16和17族杂原子化合物的合成自由基化学在过去的几十年里一直是深入研究的主题，因为它们能够在温和的条件下产生以碳为中心的自由基。相比之下，第15族杂原子化合物的合成自由基化学几乎是未知的，其合成应用也完全没有被探索过。本研究旨在阐明较重的15族杂原子化合物在自由基条件下的合成应用，以精确合成活性聚合物和有机小分子。设计并合成了几种用于活性自由基聚合的新型有机硫代宾和铋的链转移剂。他们促进了各种乙烯基单体的高度可控的活性自由基聚合，如苯乙烯衍生物、(甲基)丙烯酸酯衍生物和N-乙烯基酰胺，从而产生了活性…根据单体/链转移剂的比例和非常窄的分子量分布预测，更多的聚合物具有可控的分子量。单体家族的高度通用性和与极性官能团的高度相容性使这些化合物在合成结构明确、官能团密集的大分子方面具有很高的实用价值。观察到的高控制性归因于这些杂原子化合物对与聚合物末端自由基的均裂取代反应(简并链转移反应)的高反应性；快速反应使所有具有相似链长的聚合物链得以延长。均溶取代反应的速率常数在有机双宾中最快，其次是有机硫代双宾、有机钠和有机碘，这一顺序与这些杂原子化合物对活性自由基聚合的控制水平是一致的。它们对碳中心自由基均解取代反应也表现出了很好的反应活性。由于具有较高的反应活性，它们在活性自由基聚合反应中起到了助催化剂的作用，增加了对分子量分布的控制，并以可控的方式合成了超高相对分子质量的聚合物。这些结果清楚地表明，较重的15族杂原子化合物是很好的碳心自由基的前体，在自由基反应中也具有相当大的合成用途。较少

Synthetic radical chemistry of group 16 and 17 heteroatom compounds, such as organoselenides, tellurides, bromides, and iodides, has been the subject of intensive research over the past several decades because of their ability to generate carbon-centered radicals under mild conditions. In contrast, the synthetic radical chemistry of group 15 heteroatom compounds is virtually unknown, and their synthetic applications are totally unexplored. This research is aimed to clarify the synthetic utilities of heavier group 15 heteroatom compounds, such as organostibines and organobismuthines, under radical conditions for the precise synthesis of living polymers and small organic molecules.Several new organostibine and bismuthine chain transfer agents for living radical polymerization have been designed and synthesized. They promoted highly controlled living radical polymerization of various vinyl monomers, such as styrene derivatives, (meth)acrylate derivatives, and N-vinylamides, giving living … More polymers with controlled molecular weights as predicted by the ratio of monomer/chain transfer agent and very narrow molecular weight distributions. The high versatility for monomer families and high compatibility to polar functional groups make these compounds highly useful for the synthesis of structurally well defined macromolecules with dense functionalitics. The observed high control has been attributed to the high reactivity of these heteroatom compounds towards the homolytic substitution reaction (the degenerative chain transfer reaction) with polymer end radicals; the fast reaction makes it possible to elongate all of the polymer chains with similar chain lengths. The rate constant for the homolytic substitution reaction is fastest in organobismuthines followed by organostibines, organotelluriums, and then organoiodines, and this order is consistent with the level of control of living radical polymerization using these heteroatom compounds.Reactivities of distibines and thiobismuthines have been also examined. They have also shown excellent reactivity towards the homolytic substitution reaction with carbon centered radicals. Due to the high reactivity, they have served as cocatalysts in the living radical polymerization to increase the control of molecular weight distribution and to synthesize polymers with ultrahigh molecular weights under controlled manner.These results clearly demonstes that heavier group 15 heteroatom compounds are excellent precursors for carbon centered radicals and also possess considerable synthetic utilities in radical reactions. Less