Palladium-Catalyzed Ring-Forming Aminoalkenylation of Alkenes with Aldehydes Initiated by Intramolecular Aminopalladation

A palladium-catalyzed aminopalladation reaction followed by nucleophilic addition with aldehydes and dehydration is described. This direct and operationally simple procedure provides a rapid and reliable approach to a wide range of functionalized tetrahydroisoquinolines with high selectivity. Mechanistic studies disclosed that the nucleophilic addition, performed via a highly ordered transition-state, is the turnover-limiting step in which the inherent beta-hydride elimination of the key Csp(3)-Pd species was controlled by the confined conformation and the nucleophilicity of the Csp(3)-Pd bond was enhanced by the strong electron-donating effect of the nitrogen atom.