Synthesis of Pyrrolo[1,2-a]quinoxalines via gold(I)-mediated cascade reactions.

In this study, we developed an efficient tandem process of hydroamination and hydroarylation using a gold catalyst to enable and study the reactions between pyrrole-substituted anilines and alkynes. The gold(I)-catalyzed reactions were achieved in toluene at 80 °C over a reaction time of 1−6 h. These reactions are applicable to a variety of aromatic amino compounds and both the terminal and internal alkynes. Substituted pyrrolo[1,2-a]quinoxalines were obtained in moderate to excellent yields. A presumed mechanism involving intermolecular C−N bond formation and intramolecular nucleophilic reaction via a cationic gold complex has been proposed on the basis of the deuterium labeling studies.