Ag2O mediated N-demethylation and oxidative opening of indenopyrido[2,1-a]isoindolones. Efficient access to polysubstituted 1-azafluorenones

Abstract

Highly functionalized 1-azafluorenones were obtained from indeno[2,1-a]isoindolones through Ag₂O-mediated cascade reaction. The cascade process includes the oxidation of vicinal alcohol and dihydropyridine to generate a pyridinium intermediate which is trapped in situ by a nucleophile. Functional groups such as methoxy, thiomethyl and aldehyde survived the Ag₂O treatment whereas the dimethylamino group was partially demethylated.