Carboxylate-Assisted Formation of Aryl-Co(III) Masked-Carbenes in Cobalt-Catalyzed C-H Functionalization with Diazo Esters

Abstract

Herein we describe the synthesis of a family of aryl-Co(III)-carboxylate complexes and their reactivity with ethyl di-azoacetate (EDA). Crystallographic, full spectroscopic characterization and theoretical evidence of unique C-metalated aryl-Co(III) enolate intermediates is provided, unraveling a carboxylate-assisted formation of aryl-Co(III) masked-carbenes. Moreover, additional evidence for an unprecedented Co(III)-mediated intramolecular SN2-type C-C bond formation in which the carboxylate moiety acts as a relay is disclosed. This novel strategy is key to tame the hot reactivity of a metastable Co(III)-carbene and elicit C-C coupling products in a productive manner