Heterogenization of a Molecular Ni Catalyst within a Porous Macroligand for the Direct C–H Arylation of Heteroarenes
Y. Mohr, Marcelo Alves‐Favaro, Rémy Rajapaksha, Gaëlle Hisler, Alisa Ranscht, Partha Samanta, Chantal Lorentz, Mathis Duguet, Caroline Mellot‐Draznieks, Elsje Alessandra Quadrelli, Florian M. Wisser, J. Canivet
Abstract
Direct C–H functionalization catalyzed by a robust and recyclable heterogeneous catalyst is highly desirable for sustainable fine chemical synthesis. Bipyridine units covalently incorporated into the backbone of a porous organic polymer were used as a porous macroligand for the heterogenization of a molecular nickel catalyst. A controlled nickel loading within the porous macroligand is achieved, and the nickel coordination to the bipyridine (bpy) sites is assessed at the molecular level using IR and solid-state NMR spectroscopy. The heterogenized Ni-bpy catalyst was successfully applied to the direct and fully selective C2 arylation of benzothiophenes, thiophene, and selenophene, as well as for the arylation of free NH-indole. Recyclability of the catalyst was achieved by employing hydride activators to reach a cumulative turnover number of more than 300 after seven cycles of catalysis, which corresponds to a total productivity of 12 g of 2-phenylbenzothiophene, chosen as model target biaryl, per gram of catalyst.