Divergent Entry to C-Glycosides from Unprotected Sugars.

An efficient, divergent, and straightforward access to novel C-glycosides has been developed, namely, α-hydroxy carboxamide and carboxylic acid derivatives, via a green and scalable process from unprotected carbohydrates. The method involves condensation of 1,3-dimethylbarbituric acid with unprotected sugars followed by subsequent barbiturate oxidative cleavage in the same pot. Further expanding of the chemistry led to the development of efficient entries to diastereoisomerically pure C-glycosyl-α-hydroxy esters or amides through nucleophilic attack on a readily available and versatile key lactone intermediate.