Synthesis of glycosyl esters from phosphoroates derivatives of 2-bromosugars

This work presents the synthesis of glycosyl esters of 2-bromo-2-deoxy-D-hexopyranose, having the α-D-manno (10a–cα), β-D-gluco (11a–dβ) and α-D-gluco (11a,bα) configuration, by a stereoselective reaction between phosphoroates 3–8 and carboxylic acids 9a–d. Derivatives of 10a–c and 11a–d are formed in an overall quantitative yield, in an aprotic solvent in the presence of silver salts as a leaving group activator. The phosphoroselenoate of 3 was obtained by the condensation reaction of the triethylammonium salt of phosphoroseleno acid 2 with α-1,2-D-manno-pyranosyl dibromide 1 with high stereoselectivity. The structures of the compounds 3,10a–c and 11a–d were established by ¹H and ¹³C NMR spectra and by elemental analyses. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:292–298, 2000