Copper-catalyzed one-pot synthesis of glycosylated iminocoumarins and 3-triazolyl-2-iminocoumarins

Abstract

A general strategy was developed for the synthesis of glycosyl iminocoumarins (5a–x) in a one-pot, copper-catalyzed multicomponent reaction involving a domino reaction of sulfonyl azides, sugar alkynes, and salicylaldehydes via ketenimine intermediate formation. Similarly, glycosyl 3-triazolyl-2-iminocoumarin derivatives (6a–o) have also been synthesized in a one-pot, three component condensation via tandem “CuAAC-aldol-cyclization-dehydration” sequence. In this event, a copper-catalyzed cycloaddition reaction between 2-azidoacetonitrile and sugar alkynes furnished a triazole derivative in situ and activated the neighboring methylene group, inducing an aldol–cyclization–dehydration sequence in the presence of a salicylaldehyde. The yields were very good in all reactions.