Reaction of 5,6-cyclic sulfates derived from glycofuranoses with bases. A one-pot synthesis of 6-deoxy-hexofuranos-5-ulose derivatives

Methyl 2,3-O-isopropylidene-5,6-O-sulfuryl-α-d-mannofuranoside 1 reacted with nitrogen bases to give the corresponding aminosulfates. Strong bases such as sodium tert-butoxide or n-butyllithium afforded methyl 6-deoxy-2,3-O-isopropylidene-α-d-lyxo-hexofuranos-5-uloside 7. The reaction was optimized with sodium tert-butoxide and applied to three other 5,6-cyclic sulfates derived from aldofuranosides to give the corresponding keto-aldoses in good yields.