Monosaccharide-based water-soluble fluorescent tags

Monosaccharides are fluorescently labeled under microwave irradiation by N-(coumarin-3-carbonyl)benzotriazole 4. 1,2:3,4-di-O-isopropylidene-alpha-D-galactopyranose 9 gives 12 (90%), 1,2:5,6-di-O-isopropylidene-D-glucose 10 gives 13 (89%), 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose 11 gives 14 (65%) (all by O-acylation) and 2,3,4,5-tetra- O-pivalOyl-beta-D-galactopyranosylamine 15 gives 16 (60%) (by N-acylation). Similarly, the coumarin-containing activated lysine derivatives 7 and 8 afford the L-lysine-scaffold based coumarin labeled sugars 17, 18a,b, and 19 (67-85%) which, after removal of the diisopropylidene groups, provide water-soluble fluorescent derivatives.