Gold-Catalyzed Spirocyclization Reactions of <i>N</i> -Propargyl Tryptamines and Tryptophans in Aqueous Media

Abstract

<i>N</i>-Propargyl tryptamine and tryptophan derivatives that are readily available from both synthetic and biocatalytic approaches undergo gold-catalyzed dearomative cyclizations in aqueous media to the corresponding spirocyclic derivatives. In addition to the efficiency of the method, operating in aqueous media affords a selective entry to C2-unsubstituted spiroindolenines that have long remained unattainable by Au(I) catalysis. Moderate to excellent yields of the desired spirocyclic products bearing various substituents were obtained.