A Golden Synthetic Approach to 2-(1H-Pyrrol-1-yl)anilines and Pyrrolo[1,2-a]quinoxalines through a Gold Carbene Intermediate

Abstract

The pyrrolo[1,2-a]quinoxaline skeleton has significant potential for many biological and optical applications. Hence, in this study, unconjugated ynone derivatives are reacted with 1,2-diaminoarenes under gold-catalyzed cyclization. The reaction gives 2(1H-pyrrole-1yl)-aniline, which is a valuable starting material, and Pyrrolo[1,2-a]quinoxaline through a one-pot and single-step approach. A reaction mechanism for the formation of the pyrrolo[1,2-a]quinoxaline skeleton featuring a key gold-carbene intermediate is proposed. On the other hand, the methyl group on the C-2 position of 2(1H-pyrrole-1yl)-anilines is oxidized with SeO2, resulting in a pyrrolo[1,2-a]quinoxaline skeleton, which gives 14 different pyrrolo[1,2-a]quinoxaline derivatives.