Efficient Synthesis of Some Unsaturated [1,2,3]‐Triazole‐Linked Glycoconjugates

Thermal 1,3-dipolar cycloaddition of ethyl 4-azido-2,3,4-trideoxy-alpha-D- erythro -hex-2-enopyranosides with diethyl acetylenedicarboxylate or copper-catalyzed reaction with various functionalized alkynes gave the corresponding 1-(ethyl 2,3,4-trideoxy-alpha-D- erythro -hex-2-enopyranosid-4-yl)-1 H -1,2,3-triazole derivatives in quite good yields. These unsaturated compounds could be transformed into 1-(ethyl 2,3-di-O-acetyl-4-deoxy-alpha-D-mannopyranosid-4-yl)-1 H -1,2,3-triazoles by a simple dihydroxylation reaction. Copper-catalyzed condensation of ethyl 6-O-acetyl-4-azido-2,3,4-trideoxy-alpha-D- erythro-hex-2-enopyranoside with 1,3,5-triethynylbenzene or 1,3,5-tris(prop-2-ynyloxy)benzene afforded the corresponding trivalent glycoconjugate clusters.