Synthesis and enzyme-catalyzed hydrolysis of a radical-masked glycosylated spin-label reagent

N1-Acetoxy-2,2,6,6-tetramethylpiperidin-4-yl 2,3,4,6-tetra-O-benzyl-α- and -β-d-glucopyranosides (3-α, β) and N1-acetoxy-2,2,5,5-tetramethylpyrrolin-3-oyl 2,3,4,6-tetra-O-benzyl-α- and -β-d-glucopyranosylamines (9-α, β) were synthesized in good yield by Schmidt’s glycosylation method. Their subsequent O-debenzylation was proceeded successfully to give the desired products 1-α, and 1-β in good yield, and 2-α in a low yield, without 2-β by only short-timed hydrogenolysis in the presence of palladium-on-carbon (Pd–C) in a CHCl3–MeOH solvent system that included concentrated HCl. Upon enzyme-catalyzed hydrolysis, only 2-α was hydrolyzed by the esterase, while both of 1-α and 1-β were not hydrolyzed by any other enzyme such as lipase. These 2-α can likely be used as a new water-soluble radical-masked glycosylated spin-label reagent.