Pd(II)-catalyzed one-step construction of cycloalkane-fused indoles and its application in formal synthesis of (±)-aspidospermidine.

A highly efficient, redox-free Pd(II)-catalyzed tandem cyclization reaction initiated by intramolecular aminopalladation of alkynes followed by nucleophilic addition to nitriles is developed. This method provides a versatile approach for the synthesis of six- to eight-membered ring-fused indoles in one step and has also shown advantages in the formal synthesis of (±)-aspidospermidine.