作者:Takahiro Doba、Laurean Ilies、Wataru Sato、Rui Shang、Eiichi Nakamura
DOI:10.1038/s41929-021-00653-7
日期:——
Regioselective thienylâthienyl coupling is arguably one of the most important transformations for organic electronic materials. A prototype of ideal organic synthesis to couple two thienyl groups by cutting two CâH bonds requires formal removal of two hydrogen atoms with an oxidant, which often limits the synthetic efficiency and versatility for oxidation-sensitive substrates (for example, donor and hole-transporting materials). Here, we found that diethyl oxalate, used together with AlMe3, acts as a two-electron acceptor in an iron-catalysed CâH activation. We describe the regioselective thienyl CâH/CâH coupling with an iron(III) catalyst, a trisphosphine ligand, AlMe3 and diethyl oxalate under mild conditions. The efficient catalytic system accelerated by ligand optimization polymerizes thiophene-containing monomers into homo- and copolymers bearing a variety of electron-donative Ï motifs. The findings suggest the versatility of iron catalysis for the synthesis of functional polymers, for which the potential of this ubiquitous metal has so far not been fully appreciated. The coupling of substituted thiophenes is central to the synthesis of conducting polymers but relies on costly Pd-catalysed cross-couplings. Here, Earth-abundant iron and aluminium are shown to catalyse a regioselective thienyl CâH/CâH dimerization, enabling the synthesis of an array of Ï-conjugated polythiophenes.
地方选择性噻吩-噻吩偶联可以说是有机电子材料中最重要的转化之一。一个理想有机合成的原型是通过切断两个C-H键来偶联两个噻吩基,这需要正式去除两个氢原子,通常需用氧化剂,这往往限制了合成效率和对氧化敏感底物(例如,供体和载流子传输材料)的多样性。在这里,我们发现二乙氧基草酸盐与AlMe3联用,在铁催化的C-H活化中作为一个双电子受体。我们描述了在温和条件下,使用铁(III)催化剂、三膦配体、AlMe3和二乙氧基草酸盐进行地方选择性噻吩C-H/C-H偶联的过程。通过优化配体,该高效催化系统加速了含噻吩单体的聚合,生成了具有多种电子供给π基元的均聚物和共聚物。这些发现表明铁催化在功能聚合物合成中的多样性,这种无处不在的金属的潜力至今尚未得到充分认可。
取代噻吩的偶联对导电聚合物的合成至关重要,但依赖于昂贵的钯催化交叉偶联。在此,地球丰度的铁和铝被证明可以催化地方选择性的噻吩C-H/C-H二聚反应,从而实现一系列π-共轭聚噻吩的合成。