Anomeric spirocycles by solvent incorporation: reactions of O-peracylated (glyculopyranose and glyculopyranosyl bromide)onamide derivatives with ketones.

Reactions of O-peracetylated (α-D-galacto-heptulopyranosyl bromide)onamide and O-perbenzoylated (α-D-gluco-heptulopyranosyl bromide)onamide with ketones in the presence of silver(I) salt promoters gave the corresponding O-peracylated 1',5'-anhydro-D-glycitol-spiro-[1',5]-4-imino-2,2-disubstituted-1,3-dioxolanes. The D-galacto configured starting compounds furnished both spiro epimers, while the D-gluco counterparts yielded only configurationally inverted products. Under acidic conditions, O-perbenzoylated α-D-gluco-heptulopyranosonamide and ketones yielded the protected 1',5'-anhydro-D-glucitol-spiro-[1',5]-2,2-disubstituted-oxazolidin-4-ones, which were O-debenzoylated by the Zemplén protocol. These compounds had no inhibition against rabbit muscle glycogen phosphorlyase b.