Synthesis of glycosyl esters from phosphoroates derivatives of 2-bromosugars

This work presents the synthesis of glycosyl esters of 2-bromo-2-deoxy-D-he xopyranose, having the alpha-D-manno (10 alpha-c alpha), beta-D-gluco (11a- d beta) and alpha-D-gluco (11a,b alpha) 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 aprot ic solvent in the presence of silver salts as a leaving group activator. Th e phosphoroselenoate of 3 was obtained by the condensation reaction of the triethylammonium salt of phosphoroseleno acid 2 with alpha-1,2-D-manno-pyra nosyl dibromide 1 with high stereoselectivity. The structures of the compou nds 3,10a-c and 11a-d were established by H-1 and C-13 NMR spectra and by e lemental analyses. (C) 2000 John Wiley & Sons, Inc.