Copper-Catalyzed C5-H Sulfenylation of Unprotected 8-Aminoquinolines Using Sulfonyl Hydrazides.

The synthesis of C5-sulfenylated 8-aminoquinolines using unprotected 8-aminoquinolines and sulfonyl hydrazides is achieved via the catalysis of CuI. The reactions are hypothesized to proceed via the Cu(I)-Cu(II)-Cu(I) catalytic processes induced by aerobic oxidation and single-electron transfer on the Cu(II)-8-aminoquinoline complex. This work discloses an unprecedented step-efficient method for the synthesis of C5-sulfenylated 8-aminoquinolines bearing a useful free NH2 group.