Maegawa Yoshifumi, Inagaki Shinji
Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192, Japan.
Dalton Trans. 2015 Aug 7;44(29):13007-16. doi: 10.1039/c5dt00239g.
Heterogeneous catalysis for direct C-H borylation of arenes and heteroarenes in the combination of iridium (Ir) complex fixed on periodic mesoporous organosilica containing bipyridine ligands within the framework (Ir-BPy-PMO) and pinacolborane (HBpin) is reported. Ir-BPy-PMO showed higher catalytic activity toward the borylation of benzene with inexpensive HBpin compared to expensive bis(pinacolato)diboron (B2pin2). The precatalyst could be handled without the use of a glove box. The catalyst was easily recovered from reaction mixtures by simple filtration under air. The recovered catalyst still showed good catalytic activity for at least three more times for the borylation of benzene. A variety of arenes and heteroarenes were successfully borylated with high boron efficiency by Ir-BPy-PMO using HBpin, whereas almost no activity was observed for borylation of some heteroarenes with B2pin2. The system using Ir-BPy-PMO and HBpin was also utilized in syntheses of multi-boronated thiophene-based building blocks containing ladder-, acenefused-, and fused-thiophene skeletons. The combination of a stable and reusable solid catalyst and inexpensive HBpin is expected to be superior to conventional approaches for the development of industrial applications.
报道了在含有联吡啶配体的周期性介孔有机硅（Ir-BPy-PMO）中固定的铱（Ir）配合物与频哪醇硼烷（HBpin）组合用于芳烃和杂芳烃直接C-H硼化的多相催化。与昂贵的双（频哪醇合）二硼（B2pin2）相比，Ir-BPy-PMO对用廉价的HBpin进行苯的硼化显示出更高的催化活性。预催化剂无需使用手套箱即可处理。通过在空气中简单过滤可轻松从反应混合物中回收催化剂。回收的催化剂对苯的硼化至少还能再显示三次良好的催化活性。使用Ir-BPy-PMO和HBpin，多种芳烃和杂芳烃通过高效硼化成功实现硼化，而使用B2pin2对一些杂芳烃进行硼化几乎没有活性。使用Ir-BPy-PMO和HBpin的体系还用于合成含有梯形、苊并稠合和稠合噻吩骨架的多硼化噻吩基结构单元。稳定且可重复使用的固体催化剂与廉价的HBpin的组合有望在工业应用开发方面优于传统方法。
