Palladium-Catalyzed [3 + 2]-C-C/N-C Bond-Forming Annulation.

The synthesis of bi- and tricyclic structures incorporating pyrrolidone rings is disclosed, starting from resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxycarbonyl derivatives. This process involves an intermolecular Tsuji-Trost allylation/intramolecular nitrogen 1,4-addition sequence. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. When the newly formed annulation product carries a properly located o-haloaryl moiety at the nitrogen substituent, a further intramolecular keto α-arylation can join the cascade, thereby forming two new cycles and three new bonds in the same synthetic operation.