Redox Neutral Radical-Relay Cobalt Catalysis toward C–H Fluorination and Amination

Abstract

A redox neutral radical-relay cobalt-catalyzed intramolecular C–H fluorination of N-fluoroamides featuring the in situ formed cobalt fluorides as the latent radical fluorinating agents is reported. Moreover, the reactivity of such a cobalt catalysis could be diverted from C–H fluorination to amination by engineering substrates’ conformational flexibility. Preliminary mechanistic studies (UV–vis spectroscopy, cyclic voltammetry studies and DFT calculations, etc.) support the reaction proceeding a redox neutral radical-relay mechanism.

Cobalt‐Catalyzed Radical Hydroamination of Alkenes with N‐Fluorobenzenesulfonimides

“…Based on these experiment results and literature precedents, [7a,c-e] ap ossible Co III H-catalyzed radical hydroamination pathway was shown in Scheme 5. [12][13][14] Thecatalytic cycle begins with the oxidation of LCo II species by NFSI to deliver the LCo III Fs pecies and benzenesulfonimide radical A, [2,36,38,39] followed by the transmetalation of LCo III Fw ith TMDS forming the LCo III Hspecies. [40,41] Theresulting radical A might be trapped by Co II species to form the LCo III -NR 2 species B,w hich has been detected by high-resolution mass spectrometry (HRMS) (see supplementary materials).…”

Cobalt-catalyzed modular assembly toward multi-functionalized furan derivatives

“…13 For instance, we have recently shown that a Co(salen) complex is a competent catalyst for the intermolecular aminofluorination of alkenes 13c via a redox-neutral reaction (Scheme 1A). 14 The cobalt fluoride, 15 generated in situ by the reaction between N-fluorosulfonamide and cobalt, was proposed as the key fluorine transfer agent. Meanwhile, the Jacobsen Co(salen) complex has also been found to enable the asymmetric monofluorination of β-dicarbonyls in moderate to good enantioselectivities (Scheme 1B).…”

Iron-Catalyzed, Site-Selective Difluoromethylthiolation (−SCF2H) and Difluoromethylselenation (−SeCF2H) of Unactivated C(sp3)–H Bonds in N-Fluoroamides

“…Recently, the interception of transition-metal catalysis for the HLF-type δ-C­(sp 3 )–H bond functionalization of N -fluoroamides has received much attention because of their unique regioselectivity under mild conditions . Since the pioneering work by Cook, some elegant work on remote C­(sp 3 )–H functionalization has been disclosed with Fe, Cu, Co, and photoredox Ir catalysis. Our group also demonstrated Cu-catalyzed remote C­(sp 3 )–H cyanation and thiocyanation, respectively.…”