Dual Gold Catalysis: A Novel Synthesis of Bicyclic and Tricyclic Pyrroles from N-Propargyl Ynamides

Various N-propargyl ynamides were converted to bicylic and tricyclic pyrroles by the use of a cationic dual-activation gold catalyst. This reaction starts with the nucleophilic addition of a gold acetylide onto an ynamide triple bond at the β-position of the nitrogen atom. Thus, gold vinylidene is formed, and then a second cyclization takes place. The formation of the gold vinylidene is indicated by the evidence that not only aryl ynamides but also alkyl ynamides undergo C-H activation in these reactions.