Practical Synthesis of Phenanthrid­inones by Palladium-Catalyzed One-Pot C-C and C-N Coupling Reaction: Extending the Substrate Scope to o-Chlorobenzamides

A highly efficient construction of phenanthridinone derivatives from o‐halobenzamides was developed by using a phosphine‐free palladium catalyst in N,N‐dimethylacetamide. The domino reaction proceeds through a sequential C–C and C–N bond‐formation process in one pot. This protocol exhibits broad substrate scope and affords a series of phenanthridinones in up to 93 % yield. Importantly, the protocol could also be applied for the less reactive o‐chlorobenzamides. The approach constitutes the first example of the synthesis of phenanthridinones from this kind of substrate. Moreover, the success of a gram‐scale reaction demonstrated that this operationally simple process is scalable. A highly efficient palladium‐catalyzed phosphine‐free domino reaction for the construction of phenanthridinone derivatives using o‐halobenzamides has been developed. This protocol exhibits broad substrate scope, and a series of phenanthridinones derivatives were obtained with high yields. Importantly, this reaction system could also be applied for the less reactive and less expensive o‐chlorobenzamides.