Facile Dearomatization of Nitroquinolines through [3+2] and [4+2] Cycloaddition Reactions

An efficient method was developed for the functionalization of nitroquinolines by employing pericyclic [3+2] and [4+2] cycloaddition reactions. The facile dearomatization of the nitrated benzene ring under the action of unstabilized N-alkyl azomethine ylides and dienes led to fused heterocyclic systems. The 1,3-dipoles smoothly and selectively underwent a cycloaddition reaction with the C=C(NO2) fragment of the aromatic system if the position ortho to the nitro group was vacant, whereas the [4+2] cycloaddition of dienes required a furoxan ring to be annulated to the quinoline moiety.