Base-Mediated Cascade Annulations of β-CF ₃ -1,3-Enynamides with Tosylaminomethyl Enones: Synthesis of Angularly CF ₃ -Substituted Hexahydrocyclopenta[ <i>c</i> ]pyrrole Frameworks

A base-mediated cascade [3 + 2]/[2 + 3] annulation of β-CF₃-1,3-enynamides with tosylaminomethyl enones affording highly functionalized angularly CF₃-substituted hexahydrocyclopenta[<i>c</i>]pyrrole frameworks, which are challenging to prepare via conventional approaches, was developed. In contrast to mononucleophiles and bisnucleophiles involving allenamide intermediates, ambiphilic reagent tosylaminomethyl enones demonstrate a novel reaction pattern to β-CF₃-1,3-enynamides. The electron-withdrawing group on the nitrogen atom of β-CF₃-1,3-enynamides has a great impact on this cascade annulation.