Oxoiron(v) mediated selective electrochemical oxygenation of unactivated C-H and C[double bond, length as m-dash]C bonds using water as the oxygen source.

ABSTRACT: An efficient electrochemical method for the selective oxidation of C-H bonds of unactivated alkanes (BDE ≤97 kcal mol^-1) and C[double bond, length as m-dash]C bonds of alkenes using a biomimetic iron complex, [(bTAML)Fe^III-OH₂]^-, as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes is reported. The O-atom of water remains the source of O-incorporation in the product formed after oxidation. The products formed upon oxidation of C-H bonds display very high regioselectivity (75 : 1, 3° : 2° for adamantane) and stereo-retention (RC ∼99% for cyclohexane derivatives). The substrate scope includes natural products such as cedryl acetate and ambroxide. For alkenes, epoxides were obtained as the sole product. Mechanistic studies show the involvement of a high-valent oxoiron(v) species, [(bTAML)Fe^V(O)]^- formed via PCET (overall 2H⁺/2e^-) from [(bTAML)Fe^III-OH₂]^- in CPE at 0.80 V (vs. Ag/AgNO₃). Moreover, electrokinetic studies for the oxidation of C-H bonds indicate a second-order reaction with the C-H abstraction by oxoiron(v) being the rate-determining step.

SUBMITTER: Chandra B 

PROVIDER: S-EPMC8162932 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature