Cobalt-Catalyzed Switchable Intramolecular Thioenolization/C-H Thiolation and C(sp 2 )-H/C(sp 3 )-H Dehydrogenative Coupling.

Mild cobalt-catalyzed switchable regioselective and chemoselective thioenolization/C-H thiolation and C(sp(2))-H/C(sp(3))-H dehydrogenative couplings of N-aryl-N-alkyl-thioamides are developed, providing 2-methylene-2,3-dihydrobenzo[d]-thiazoles and thio-oxindoles in moderate to excellent yields from the same precursors, respectively. Details mechanistic studies suggest that the thioenolization/C-H thiolation process involves a radical mechanism, whereas the C(sp(2))-H/C(sp(3))-H dehydrogenative coupling might proceed through an electrophilic cobaltation(III) pathway. Thus, the selectivity for either product is achieved by accessing unique catalytic cycles involving different valence states for cobalt.