Construction of Cyclopenta[ <i>b</i> ]pyridine Frameworks via Pd(0) π-Lewis Base-Initiated Cascade Reaction of Enyne-Tethered Malononitriles

A Pd(0) π-Lewis base-initiated cascade transformation of 1,3-enyne-tethered malononitriles is disclosed, proceeding through intramolecular vinylogous addition of the nucleophilicity-enhanced alkyne moiety to a pendent cyano group, <i>cis</i>/<i>trans</i> isomerization, and Suzuki coupling, followed by 6π-aza-electrocyclization and oxidative aromatization. A range of cyclopenta[<i>b</i>]pyridines are constructed straightforwardly, while azafluorenes are obtained instead in the presence of formic acid. Moderate enantioselectivity is also achieved using a chiral sulfinamide-phosphine ligand.