A recyclable rhodium catalyst anchored onto a bipyridine covalent triazine framework for transfer hydrogenation of N-heteroarenes in water

Covalent triazine frameworks (CTFs) based on polydentate ligands are highly promising supports to coordinate well-defined active metal complexes, hereby combining the well-known reactivity of homogeneous catalysts with the robustness and recyclability of heterogeneous catalysts. Herein, we describe the immobilization of a half-sandwich Rh(iii) complex onto a bipyridine-based CTF and its application for the transfer hydrogenation of N-heteroarenes in water with benign sodium formate as the hydrogen source. The heterogenized catalyst exhibited excellent activity toward a wide variety of quinoxalines and various other N-heteroarenes. Moreover, the catalyst maintained high activity during recycling and could be implemented in a continuous flow synthesis.