Cobalt-Catalyzed Switchable Intramolecular Thioenolization/C–H Thiolation and C(sp<sup>2</sup>)–H/C(sp<sup>3</sup>)–H Dehydrogenative Coupling
Yao Zhi, Zhongliang Cai, Long Zhen, Liqin Jiang
Abstract
Mild cobalt-catalyzed switchable regioselective and chemoselective thioenolization/C–H thiolation and C(sp2)–H/C(sp3)–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(sp2)–H/C(sp3)–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.
Topics & Concepts
Intramolecular forceChemistryCatalysisCobaltCoupling (piping)Medicinal chemistryStereochemistryOrganic chemistryMechanical engineeringEngineeringSulfur-Based Synthesis TechniquesCatalytic C–H Functionalization MethodsSynthesis and Catalytic Reactions