Copper and palladium mediated C-H chlorination on 8-acylaminoquinoline scaffolds

Depending on the metal complexes employed, regiodivergent C-H direct chlorination on 8-acylaminoquinolines could be realized. While the stoichiometric CuCl2/base persistently gave the C5-monochlorination, the Pd(II)-catalyzed chlorination by using N-chlorosuccinimide (NCS) as a chlorine source led to variable results mainly relying on the substitution pattern of the 8-acylaminoquinolines and the loading of NCS. This work demonstrated not only an unprecedented access to divergently halogenated quinolines, but also a less studied C(sp2)-H functionalization mode, namely the single-electron transfer (SET) mediated C(sp2)-H functionalization.