Tertiary Enamide-Promoted Diastereoselective Domino: N-Acyliminium Ion Trapping and Nazarov Cyclization.

N-Acyliminium ions generated from enamidyl vinyl ketones provided cyclopentenoid-fused diazepines diastereoselectively using BF3·Et2O in one pot through a domino N-acyliminium ion trapping/Nazarov reaction, simultaneously generating three new stereogenic centers. The particular structural design of the cross-conjugated dienone dictates the torquoselectivity observed in this polarized Nazarov reaction. Various N-bridgehead polycyclic scaffolds of putative pharmacological interest were obtained. Cyclic voltammetry was used to support the preferred reaction sequence within this domino reaction.