Diverting the Mannich reaction to access 2,2-disubstituted indolin-3-ones by merging 1,2-aryl migration and copper-catalyzed aerobic oxidation

Three typical substrates for the Mannich reaction, p -anisidine, aldehyde, and a nucleophile, did not afford the predictable linear Mannich base under an aerobic copper oxidation condition, but rendering a 2,2-disubstituted indolin-3-one product.