ELECTROCHEMICAL VERSUS ANIONIC OXYGENATION OF AZATHYMINE DERIVATIVES

Pymetrozine (1) was converted to hemiaminal 2 in low to moderate yield by trapping its dianion with oxygen followed by reduction with ferrou s salts. Pymetrozines 18 and 19 failed to undergo this type of oxygena tion. All three pymetrozines were oxidized electrochemically at C5 to methyl hemiaminals 20, 21, and 22, respectively. Hydrolysis of 20 to 2 was accomplished under either acid-or base-catalyzed conditions in ex cellent yields, whereas the hydrolysis of methyl hemiaminals 21 and 22 was best performed under basic conditions. Soil metabolites of pymetr ozine 1, hemiaminals 2 and 3, were prepared on a medium scale and in e xcellent yields. Linear sweep voltammetry data and conditions for prep arative-scale electrochemistry are furnished for the precursory pymetr ozines. Complete experimental and spectral data are provided for all n ew compounds, and the relative merits of anionic versus electrochemica l oxidations for alkyl amides are discussed. A cautionary note is prov ided with the description of the conditions for large-scale anionic ox ygenation because of potential explosive hazards.