Ruthenium-Catalyzed Remote C–H Sulfonylation of <i>N</i>‑Aryl-2-aminopyridines with Aromatic Sulfonyl Chlorides

A ruthenium-catalyzed remote sulfonylation at the C5 position of the pyridine group of N-aryl-2-aminopyridines with aromatic sulfonyl chlorides is described. The mechanistic and deuterium labeling studies clearly reveal that the ruthenametallacycle is a key intermediate in the reaction, which forms via the C–H bond activation. The DFT calculation supports that the C5 position of the 2-aminopyridine group carries a more negative charge (−0.304) as compared with other carbons in the metalacycle intermediate.