Electrochemically Triggered Hole-catalytic Benzylic Substitution Reaction at a Polymer Chain Containing β-O-4 Linkage
作者:Rumi Izumiya、Mahito Atobe、Naoki Shida
DOI:10.1246/bcsj.20230019
日期:——
Organic electrosynthesis enables clean, sustainable, and unique molecular transformations; however, its application to polymeric materials is restricted by their sterically demanding nature, which hinders quantitative electron transfer at the electrode surface. Herein, we report, for the first time, a hole-catalytic reaction triggered via anodic oxidation as a key strategy for achieving a high degree of electrochemical transformation in polymeric materials. Careful molecular and reaction design enabled hole-catalytic benzylic substitution, with an 88% degree of substitution, in a sterically hindered polymer, via an electrolytically generated radical cation. Mechanistic studies revealed that through-space delocalization of holes between neighboring aromatic systems contributes significantly to the stabilization of the radical cation species and intra-chain hole transfer. Thus, this study establishes hole catalysis as an effective strategy for the electrochemical transformation of polymers, which may aid the design of sustainable electrosynthetic strategies for functional macromolecules.
有机电合成可以实现清洁、可持续且独特的分子转化;然而,由于聚合物材料的空间位阻性质,阻碍了电极表面的定量电子转移,从而限制了其在聚合物材料中的应用。在此,我们首次报告了通过阳极氧化引发的空穴催化反应,作为实现聚合物材料高度电化学转化的一种关键策略。通过仔细的分子和反应设计,在空间位阻聚合物中,通过电解产生的自由基阳离子实现了空穴催化苄基取代,取代度为88%。机理研究表明,相邻芳香系统之间的空穴穿隧分布极大地促进了自由基阳离子物种的稳定性和链内空穴转移。因此,这项研究将空穴催化确立为聚合物电化学转化的有效策略,有助于设计功能大分子的可持续电合成策略。