Fenton-like Chemistry by a Copper(I) Complex and H 2 O 2 Relevant to Enzyme Peroxygenase C-H Hydroxylation.

Lytic polysaccharide monooxygenases have received significant attention as catalytic convertors of biomass to biofuel. Recent studies suggest that its peroxygenase activity (i.e., using H ₂ O ₂ as an oxidant) is more important than its monooxygenase functionality. Here, we describe new insights into peroxygenase activity, with a copper(I) complex reacting with H ₂ O ₂ leading to site-specific ligand-substrate C-H hydroxylation. [Cu ^I (TMG ₃ tren)] ⁺ ( 1 ) (TMG ₃ tren = 1,1,1-Tris{2-[ N ² -(1,1,3,3-tetramethylguanidino)]ethyl}amine) and a dry source of hydrogen peroxide, ( o -Tol ₃ P═O·H ₂ O ₂ ) ₂ react in the stoichiometry, [Cu ^I (TMG ₃ tren)] ⁺ + H ₂ O ₂ → [Cu ^I (TMG ₃ tren-OH)] ⁺ + H ₂ O, wherein a ligand N -methyl group undergoes hydroxylation giving TMG ₃ tren-OH. Furthermore, Fenton-type chemistry (Cu ^I + H ₂ O ₂ → Cu ^II -OH + ·OH) is displayed, in which (i) a Cu(II)-OH complex could be detected during the reaction and it could be separately isolated and characterized crystallographically and (ii) hydroxyl radical (·OH) scavengers either quenched the ligand hydroxylation reaction and/or (iii) captured the ·OH produced.