Abstract
Herein, we report that copper-(II) trifluoromethanesulfonate [Cu-(OTf)(2)], a stable, versatile, and dual-purpose catalyst, efficiently catalyzed the acetylation of l-sorbose under various conditions following metal trifluoromethanesulfonate screening. Regioselectivity is critically governed by solvents: solvent-free reactions favor the open-chain keto-sorbopentaacetate, whereas coordinating solvents direct acetylation toward the cyclic α-l-sorbopyranosyl tetraacetate. These findings underscore the pivotal role of solvents in steering reaction pathways, enabling selective and sustainable synthesis of structurally distinct sugar derivatives while using a minimal amount of catalysts.