D-MANNOFURANOSE 2,3-CARBONATE. PREFERRED SIZE OF THE SUGAR RING IN SOME FUSED-RING DERIVATIVES

Open Access
Publisher Website
Google Scholar
Abstract
Treatment of 6-O-trityl-D-mannose with phosgene gives 6-O-trityl-D-mannose 2,3-carbonate (II), which on partial hydrolysis, yields D-mannose 2,3-carbonate (VI). Chemical properties of II and VI agree with the proposition that fusion of the cyclic carbonate group at the 2- and 3-positions of D-mannose converts the latter to a furanose derivative. Nuclear magnetic resonance spectral evidence supports the furanoid assignment and indicates also that in aqueous solution VI does not rearrange significantly to a pyranose form. Substantial disagreement is found between proton-proton coupling observed for VI and corresponding data predicted from the Karplus curve. A similar situation is encountered with a related fused-ring derivative, 2,3-O-isopropylidene-L-rhamnose.5-O-Methyl-D-mannofuranose has been synthesized via methylation of II. 5,6-Di-O-acetyl-α-D-mannofuranosyl bromide 2,3-carbonate (VIII), prepared from VI, permits synthesis of either of the anomeric methyl D-mannofuranosides. On treatment of VIII with methanol in the presence of excess sodium the α-D-glycoside is obtained, whereas in the presence of silver oxide a β-D-anomeric derivative is formed.

This publication has 3 references indexed in Scilit: