Palladium-Catalyzed Hydrocarbonylative Cyclization Enabled by Formal Insertion of Aromatic C═N Bonds into Pd-Acyl Bonds.

An efficient new formal insertion strategy via combination of reductive elimination and oxidative addition sequence was reported, in which the transient N-acyliminium ions formed via hydrocarbonylation function as key intermediates. This strategy has enabled a novel palladium-catalyzed hydrocarbonylative cyclization of azaarene-tethered alkenes or dienes via sequential insertion of a C═C bond, CO, and a C═N bond into palladium-hydride bonds. This method provides a new and highly efficient synthetic approach to quinolizinones and its derivatives with extended π-conjugated systems, possessing tunable emission wavelengths and good photoluminescence capabilities.