Arylation of Pyridines via Suzuki-Miyaura Cross-Coupling and Pyridine-Directed C-H Activation Using a Continuous-Flow Approach

Suzuki-Miyaura cross-coupling reactions between heteroaryl bromides and arylboronic acids were performed employing a continuous-flow approach using a simple flow reactor designed in-house. Pd(PPh3)(4) was used as catalyst, and arylboronic acids containing both electron-withdrawing and electron-donating groups were applied. The coupling process required 23 minutes of residence time to be completed and generally good yields were obtained. Subsequent arylation of 2-phenyl pyridine was carried out via a C-H activation strategy using substituted bromobenzene compounds and a ruthenium(II) catalyst. To the best of our knowledge in this work we present for the first time the possibility of performing intermolecular C-H activation in a continuous-flow system.