Experimental Detection of One Case of Benzene Epoxidation by a Peroxy Radical and Computational Prediction of Another

Abstract

Reaction of the beta-styryl radical with O2 in benzene results in a low yield of benzene oxide, which is shown by isotopic labeling to arise from the solvent. Ab initio and DFT calculations elucidate the mechanism of this reaction, and identify the properties of other radicals that should be more effective promoters of the reaction. The CN radical is found to be one candidate.

Intramolecular Addition of Cysteine Thiyl Radical to Phenylalanine and Tyrosine in Model Peptides, Phe (CysS•) and Tyr(CysS•): A Computational Study

“…39 Another example for the chemically important weak interaction of a radical with an aromatic ring was recently presented for the intermolecular addition of peroxyl radicals to benzene en route to the formation of benzene oxide. 40 Here, cyclohexadienyl radicals were theoretically and experimentally supported (through products) even though associated with a positive ∆G ) 20.6 kcal/mol. Theoretically, the π-complex between CysS • and Phe could undergo intramolecular electron transfer to yield CysSand Phe +• , followed by rapid deprotonation of Phe +• to benzyl radical and protonation of CysSto CysSH.…”

“…Another example for the chemically important weak interaction of a radical with an aromatic ring was recently presented for the inter molecular addition of peroxyl radicals to benzene en route to the formation of benzene oxide . Here, cyclohexadienyl radicals were theoretically and experimentally supported (through products) even though associated with a positive Δ G = 20.6 kcal/mol.…”

Synthesis and Desymmetrization of meso Tricyclic Systems Derived from Benzene Oxide

“…The direct oxidative dearomatization of aromatic feedstocks to arene oxide derivatives has primarily been accomplished via enzymatic pathways, but in most cases, the presence of electron-withdrawing groups is needed in order to isolate the desired oxides and prevent rearomatization . Nonenzymatic pathways have been limited by low yields and operational practicality . To date, an efficient, dearomative, nonenzymatic synthesis of benzene oxide has not been reported.…”