Gold(I)-Catalyzed and PTSA-Promoted Cycloisomerization of Ynamides to Access Pyrrole Substituted alpha,beta-Unsaturated Ketones

Substituted pyrroles are prevalent aromatic ring systems encountered in numerous natural products and bioactive molecules. Herein, a novel ynamide scaffold has been designed, synthesized and subsequently applied to an unprecedented gold-catalyzed and para-toluenesulfonic acid (PTSA)-assisted cascade cycloisomerization reaction for the synthesis of beta-pyrrole substituted alpha,beta-unsaturated ketones. Notably, the reaction is stereoselective, offering E-isomer as major product with low to moderate yield.