Tunable stereoselectivity in the synthesis of α- and β-aryl glycosides using 1,2-α-anhydrosugars as glycosyl donors.

The stereochemical course of O-glycosidation of 1,2-α-d-anhydrosugars (glycal epoxides) with phenols can be tuned by varying the metal ion of the base. While the reaction of 1,2-α-d-anhydrosugars with phenols mediated by trimethylaluminium leads exclusively to 1,2-cis-α-O-aryl glycosides, similar reaction mediated by caesium carbonate gives exclusively 1,2-trans-β-O-aryl glycosides. In contrast, reaction with phenoxides generated from Grignard reagent and calcium salts affords mixture of the anomers.

Montmorillonite K-10 clay-catalyzed Ferrier rearrangement of 2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol: a few unexpected domino transformations.

Montmorillonite K-10 clay-catalyzed substitution reactions of 3,4,6-tri-O-alkyl-2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-acetyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol with a few alcohols and phenols are described. The reactions of 2-C-hydroxymethyl-d-glycals with phenols were similar to those of 2-C-acetoxymethyl-d-glycals and afforded pyrano[2,3-b]benzopyrans. This montmorillonite K-10 clay-catalyzed transformation is facile both under ambient (Method 1) and microwave conditions (Method 2).

Trifluoroacetic acid-mediated facile transformation of 2-C-hydroxymethyl-D-glycals to chiral pyrano[2,3-b]benzopyrans.

Treatment of 2-C-hydroxymethyl-D-glycals with phenols in trifluoroacetic acid at ambient temperature leads to an extremely facile transformation affording chiral pyrano[2,3-b]benzopyrans in high yields.

Inhibition of O-GlcNAcase by a gluco-configured nagstatin and a PUGNAc-imidazole hybrid inhibitor.

Synthesis of a PUGNAc-imidazole hybrid and its characterization as an inhibitor of human O-GlcNAcase through enzyme kinetics and X-ray structural analysis.

Stereoselective synthesis of a C-glycosylic compound (a "methyl C-glycoside") through a regioselective free-radical ring-opening reaction. A single-crystal X-ray structure determination.

Readily available 3,4,6-tri-O-acetyl-D-glucal was converted to 2,6-anhydro-5,7-O-benzylidene-1,3,4-trideoxy-D-arabino-hept-3-enitol, a methyl C-glycosylic compound. Cyclopropanation of 4,6-O-benzylidene-D-glucal, followed by tributylstannyl radical-mediated regioselective ring opening of the 1,2-cyclopropano sugar led to a 2,6-anhydro-1-deoxyheptose, (a "methyl C-beta-D-glycoside"). The stereochemistry of the 1,2-cyclopropano sugar and the "methyl C-glycoside" were confirmed by single-crystal X-ray diffraction studies.