Hwang Soon-Hyeok, Choi Tae-Lim
Department of Chemistry, Seoul National University Seoul 08826 Korea
Chem Sci. 2020 Dec 8;12(7):2404-2409. doi: 10.1039/d0sc06138g.
[3,3]-Sigmatropic rearrangement is a powerful reaction to form C-C bonds stereospecifically; however, owing to intrinsic simultaneous bond formation and breakage, this versatile method has not been utilized in polymerization. Herein, we report a new tandem diaza-Cope rearrangement polymerization (DCRP) that can synthesize polymers with defect-free C-C bond formation from easy and efficient imine formation. A mechanistic investigation by H NMR experiments suggests that this polymerization proceeds by a rapid DCR process, forming an enantiospecific C-C bond that occurs almost simultaneously with imine formation. This polymerization produces not only highly stable polymers against hydrolysis due to resonance-assisted hydrogen bonds (RAHBs) but also chiral polymers containing enantiopure salen moieties, which lead to high-performance Zn-selective turn-on chemosensors with up to 73-fold amplification. We also found that their optical activities and sensing performances are heavily dependent on the reaction temperature, which significantly affects the stereoselectivity of DCR.
[3,3]-σ迁移重排是一种能够立体专一性地形成碳-碳键的有效反应;然而,由于其固有的同时形成和断裂键的特性,这种通用方法尚未应用于聚合反应。在此,我们报道了一种新的串联二氮杂-Cope重排聚合反应(DCRP),该反应能够通过简单高效的亚胺形成反应,合成具有无缺陷碳-碳键的聚合物。通过1H NMR实验进行的机理研究表明,这种聚合反应通过快速的DCR过程进行,形成对映体特异性的碳-碳键,该过程几乎与亚胺形成同时发生。这种聚合反应不仅产生了由于共振辅助氢键(RAHBs)而具有高度水解稳定性的聚合物,还产生了含有对映体纯的双水杨醛缩乙二胺部分的手性聚合物,这些聚合物导致了具有高达73倍放大倍数的高性能锌选择性开启型化学传感器。我们还发现它们的光学活性和传感性能在很大程度上取决于反应温度,反应温度会显著影响DCR的立体选择性。