Base-mediated ynone-isocyanide [3+2] cycloaddition: a general method to 2,3,4-tri-substituted 1--pyrroles and bis-pyrroles.

A transition-metal-free and base-promoted one-pot synthesis of 2,3,4-trisubstituted 1--pyrroles has been developed. The reaction occurs through the [3+2] cycloaddition of differently functionalized ynones and isocyanides. The reaction's advantageous features are operational simplicity, atom economy, and functional group tolerance with broad substrate scope. In addition, 1,3-bis-pyrrole formation and gram-scale synthesis were also achieved. Furthermore, the synthetic utility of the products was also investigated isocyanide insertion and pyrrole-triazole hybrid formation in good yield.