PyBroP/base-promoted one-pot three-component sequential decarboxylative addition reaction of β-keto acids, isatylidene malononitriles and pyridine <i>N</i> -oxides

A PyBroP/base-promoted three-component sequential decarboxylative nucleophilic addition protocol has been developed. Under the optimized conditions, a wide array of β-keto acids, isatylidene malononitriles and pyridine <i>N</i>-oxides couple efficiently to deliver the desired 3,3-disubstituted oxindole-fused pyridine derivatives in moderate to excellent yields. This method features good functional group tolerance, high positional selectivity, mild reaction conditions, and a one-pot procedure. The methodology can be scaled up to the gram scale, and the synthetic utility of the product was further validated. Control experiments have also been carried out to elucidate the plausible mechanistic pathway.