High‐Valent Cobalt‐Difluoride in Oxidative Fluorination of Saturated Hydrocarbons.

Das, Agnideep; Twamley, Brendan; Kelly, Oscar R.; Panda, Chakadola; Richardson, Paul; McDonald, Aidan R.

The heme paradigm where Fe=O acts as the C−H oxidant and Fe−OH rebounds with the formed carbon‐centered radical guides the design of the prototypical synthetic hydroxylation catalyst. We are exploring methods to evolve beyond the metal‐oxo oxidant and hydroxide rebound, to incorporate a wider array of functional group. We have demonstrated the application of CoII(OTf)2 (10 mol% catalyst; OTf=trimfluoromethanesulfonate) in combination with polydentate N‐donor ligands (e. g. BPMEN=N,N′‐dimethyl‐N,N′‐bis(pyrid‐2‐ylmethyl)ethane‐1,2‐diamine) and Selectfluor in the oxidative fluorination of saturated hydrocarbons in high yields. The addition of CsF to the reaction mixture induced near‐quantitative yields of fluorinated saturated hydrocarbons (>90 % yield of fluorinated product). For 1‐hydroxy, 1‐acetyl, 1‐carboxy‐, and 1‐acetamido‐adamantane, we demonstrated selective fluorination at the 3‐position. We propose two mechanisms for the CoII‐catalyzed reaction: either (i) an N‐radical, derived from Selectfluor, acted as the C−H oxidant followed by radical rebound with CoIII−F; or (ii) a CoIV−(F)2 species was the C−H oxidant followed by radical rebound with CoIII−F. Our combined spectroscopic, kinetic, and chemical trapping evidence suggested that an N‐radical was not the active oxidant. We concluded that a CoIV−(F)2 species was the likely active oxidant and CoIII−F was the likely F‐atom donor to a carbon centered radical producing a C−F bond.

COBALT; FLUORINATION; FLUORINE; CATALYSTS; FUNCTIONAL groups; RADICALS (Chemistry); CHEMICAL reactions; ALKANES

Angewandte Chemie, 2025, Vol 137, Issue 10, p1

0044-8249

Academic Journal

10.1002/ange.202421157