Visible Light Photocatalysis of Carbon–Carbon σ‑Bond Anaerobic Oxidation of Ketones with Water by Cobalt(II) Porphyrins

CoII(por)
(por = porphyrinato dianion) reacted selectively
with isopropyl ketones at the carbon (CO)–carbon (α)
bond at room temperature to give high yields of CoIII(por)
acyls and the corresponding oxidized carbonyl compounds in up to 89%
yields. CoIII(por)­OH is proposed to be the C–C bond
activation (CCA) intermediate. The stoichiometric reaction is further
developed into the photocatalytic CCA using both UV and visible light
sources (λ 405 nm). Under ambient conditions, the photocatalytic
C–C oxidation of 2,6-dimethylcyclohexanone gives 2-heptanone
in up to 24 turnovers in the presence of isopropyl alcohol as the
H atom donor and H2O as the oxidant. Various isopropyl
ketones successfully undergo photocatalysis.