Palladium-catalyzed intramolecular C–H amination using aluminum nitrate as the oxidant†

Abstract

A palladium catalyzed intramolecular C(sp²)–H amination using a readily available aluminum nitrate (Al(NO₃)₃·9H₂O) as the oxidant is reported. The C–H amination is promoted by in situ nitration of the quinoline directing group (DG). The oxindole products can be efficiently converted into novel polycyclic compounds (up to 7 fused rings) via a sequential reduction/cyclization involving the DG. Mechanistic studies indicate that nitration of the quinoline DG favors the following activation of γ-aryl C(sp²)–H bonds over β-methyl C(sp³)–H bonds.