Pd(II)-Catalyzed One-Step Construction of Cycloalkane-Fused Indoles and Its Application in Formal Synthesis of (±)-Aspidospermidine
摘要:
A highly efficient, redox-free Pd(II)-catalyzed tandem cyclization reaction initiated by intramolecular amino-palladation of alkynes followed by nucleophilic addition to nitrites 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.
method for cyclization of alkynes is described. The reaction cascade involves the intermolecular addition of a phenylthiyl radical to a terminal triple bond generating an alkenylradical, followed by a 1,5-hydrogen atom transfer and a 5-exo-trig radicalcyclization. This very efficient tin-free procedure allows one to prepare highly functionalized cyclopentane derivatives as well as fused bicyclic and