A highly selective NHC-catalyzed Michael addition of alkanethiols or thiophenol to 2-nitro-d-galactal compounds for the synthesis of 2-nitro-thiogalactoside derivatives has been developed for the first time. A wide variety of 1,2-cis-2-nitro-thiogalactosides can be prepared in good to excellent yields and high to excellent α-selectivities.
Key words
N-heterocyclic carbenes - thiols - glycosylation - diastereoselectivity - catalysis