Enantioselective [4 + 2] Annulation Reaction of C1-Ammonium Enolate and Azadiene for 3,4-Dihydroquinolinones...

Here, we describe a practical and mechanistically intriguing enantioselective synthesis of dihydroquinolinones through an asymmetric [4 + 2] annulation process utilizing an activated ester-derived transient C1-ammonium enolate and azadiene intermediates. Additionally, dihydroquinolinones may be further transformed into tetrahydroquinoline, dihydrothioquinolinones pharmacophores, and δ-amino ester building blocks through postmodification techniques. The method is practical and scalable, eliminates the use of transition metals or expensive catalysts, and provides the opportunity to access a variety of α-arylated enantioenriched dihydroquinolone and tetrahydroquinoline products with a variety of electronically diverse substituents.