Regioselective synthesis of vinylic derivatives of common monosccarides through their activated stannylene acetal intermediates

The regioselective C-2-O-acrylation and metacrylation of methyl 4,6-O-benzylidene-alpha-D-glucopyranoside and methyl 4,6-O-benzylidene-alpha-D-galactopyranoside through their corresponding organotin intermediates have been studied. Regioselectivity was achieved through the formation of a tin chelate of the 2,3-diols. Thus, methyl 4,6-O-benzylidene-alpha-D-glucopyranoside and methyl 4,6-O-benzylidene-alpha-D-galactopyranoside were reacted with dibutylstannylene to give the corresponding dibutylstannylene acetal intermediates that were then reacted in a regioselective manner with acryloyl chloride or metacryloyl chloride in the presence of triethylamine (TEA) or pyridine to give the vinylic type monomeric compounds. The monomeric products containing glucose and galactose units from each reaction were separated by column chromatography using a gradient of n-hexane and ethyl acetate as eluant. The structure of the obtained compounds were confirmed using (1)H-, (13)C- and 2D NMR spectroscopy.