Ruthenium-catalyzed remote C5-sulfonation of N-alkyl-8-aminoquinolines.

There is an increasing demand for the methodologies of positionally selective remote C-H functionalizations. We herein report the ruthenium-catalyzed remote C5-selective sulfonation of 8-aminoquinoline derivatives. Moderate to high yields were obtained with different substituted substrates. The catalytic system exhibited a high regio-selectivity, as well as good functional group tolerance. Mechanistic study supported a radical pathway. A bifunctional ruthenium-catalytic cycle is proposed.