Mechanism of Ester Formation in the Photosensitized Oxidation of Diazomethanes. Carbonyl Oxides Do Not Isomerize to Dioxiranes in Solution

Article abstract of DOI:10.1021/jo00258a002

Formation of esters in the photooxidation of diazomethanes has been studied mechanistically.Unimolecular rearrangement of carbonyl oxides via dioxiranes as often proposed was ruled out clearly by 18O-tracer experiments.For the case of alkylphenyldiazomethanes, the rearranged alkyl benzoates were shown to be formed by a radical chain decomposition involving alkoxyl radicals as a chain carrier.The mechanism was confirmed chiefly by the 18O-tracer study and crossover experiments in the formation of esters.Other cases as reported to involve a rearrangement of carbonyl oxides to form esters or anhydrides were demonstrated to be the result of the Baeyer-Villiger oxidation by the oxide intermediates.The barrier preventing the isomerization of carbonyl oxides to more stable dioxiranes is discussed.