A Study on the Mechanism and Scope of the Radical-mediated Oxidation of Arylacetoacetates

Article abstract of DOI:10.1016/0040-4020(95)00576-T

Arylacetoacetate 1a undergoes an oxidative degradation in the presence of KtBuO, THF, catalytic I2 and O2, to give keto ester 4 as major compound.Hydrolysis and decarboxylation of this intermediate led to the corresponding arylcarboxylic acid 3a in satisfactory overall yields.By experiments conducted in the presence of 18O2, incorporation of atmosphere oxygen into the benzylic position of 4 was evidenced.Furthermore, spin-trap experiments showed that benzyl radical 7 was generated in the reaction medium, which supports its role as intermediate in the pathway leading to the observed oxidation products.A plausible mechanism for this process is presented.On the other hand, appropriate conditions for achieving the alkylation of these arylacetoacetates with no concomitant formation of oxidation side-products are reported.Finally, arylacetates suffer also this degradative oxidation process leading to the corresponding arylcarboxylic acids without isolation of the intermediate keto ester derivative.