Organoboron-Monosaccharides, XIV Routes to α-and β-D-Mannofuranosyl β-D-Mannofuranosides

Abstract

Abstract Stereoselective glycosylations of 2,3:5,6-di-O-ethylboranediyl-α-D-mannofuranosyl bromide (1) by two independent routes involving 1-O-tri-n-butyl-stannyl and 1-O-triethylborate α-D-mannofuranosyl derivatives give α-D-mannofuranosyl /β-D-mannofuranoside (8a) after deprotection. β-D-Mannofuranosyl β-D-mannofuranosides can be prepared by reaction of 1 with the sodium triethylborate derivative of 2,3:5,6-di-O-isopropylidene-β-D-mannofuranose (11) and by reacting 1 with hexabutyldistannoxane. The latter approach allows the synthesis of β-D-mannofuranosyl β-D-mannofuranoside (8b) after total deprotection.