A convenient method for C-glycosidation (alkynylation) with various silylacetylenes to D-glucal by iodine molecule via iodo-oxonium intermediates provided exclusively the a-acetylene glycoside products. Eleven successful examples are shown under this condition. (C) 2003 Elsevier Ltd. All rights reserved.
Epimerization of C-1 alkynyl group on pyranose ring through dicobalt hexacarbonyl complexes
Alkynyl group attached on the C-1 position of pyranose ring was epimerized through dicobalt hexacarbonyl complex with trifluoromethane sulfonic acid. Three steps involving complexation, acidic transformation and decomplexation afforded overall epimerization.