Gold-Catalyzed Intramolecular Coupling Reduction for Direct Synthesis of Indole-Fused Iminosugars.

Abstract

In the presence of Hantzsch ester and with JohnPhosAuCl/AgOMs as catalysts, a series of indole-fused iminosugars were obtained in good yields by the intramolecular reductive coupling reaction of iminosugar C-glycoside, in which the terminal alkyne could be coupled with indole and further reduced to methyl. The substrates of iminosugar C-glycosides were conveniently prepared by a three-component reaction of tosylated/mesylated sugar, propargylamine, and indole derivatives. The advantages of this protocol are its simplicity and efficiency in constructing the complex indole-fused iminosugars.