Copper-Catalyzed [5 + 1] Cyclization of o -Pyrrolo Anilines and Heterocyclic N -Tosylhydrazones for Access to Spiro-dihydropyrrolo[1,2- a ]quinoxaline Derivatives.

An inexpensive copper-catalyzed sequential reaction process, proceeding via a nucleophilic attack of amine to Cu-carbene generated in situ from heterocyclic N -tosylhydrazone precursors followed by a 1,2-H shift/oxidative cyclization cascade of N -ylides, has been described, smoothly generating the corresponding structurally various spiro-dihydropyrrolo[1,2- a ]quinoxaline derivatives. Furthermore, the significance of this protocol can be also highlighted by its diverse conversions of the synthetic compounds to the potentially bioactive molecules such as the 2-substituted pyrrolo[1,2- a ]quinoxalins.