A sequential Ugi–Smiles/transition-metal-free endo-dig Conia–ene cyclization: the selective synthesis of saccharin substituted 2,5-dihydropyrroles†
Abstract
A convenient, transition-metal-free access to a series of unprecedented saccharin substituted 2,5-dihydropyrroles is reported. This approach employs a post-Ugi–Smiles 5-endo-dig Conia–ene cyclization sequence under mild conditions while incorporating a series of readily available precursors and sodium azide substrate as a catalyst for the cyclization step. The method provides a broad scope of 2,5-dihydropyrrole derivatives in good yields.