Vinyl Sulfones as Alkyne Equivalents: A Metal-Free Eliminative Azide-Olefinic Cycloaddition Strategy as the Core Reaction for the Synthesis of 5-Vinyl- and <i>N</i> -Vinyl-1,5-Disubstituted 1,2,3-Triazoles

For the incorporation of the vinyl moiety at the C5 or/and N1 of 1,5-disubstituted 1,2,3-triazoles, specially designed vinyl sulfones are used as the alternative alkyne source. These 1,5-disubstituted 1,2,3-triazoles were synthesized through regioselective, metal-free "Eliminative Azide-Olefinic Cycloaddition" of vinyl sulfones and organic azides in a biodegradable, eco-friendly aqueous ionic liquid medium. Further synthetic manipulation of these specially functionalized 1,5-disubstituted 1,2,3-triazoles afforded mono-, bis-, and tris-5-vinyl-1,5-disubstituted 1,2,3-triazoles and C/<i>N</i>-divinyl-1,5-disubstituted 1,2,3-triazoles. Carbohydrate-functionalized 5-vinyl- and <i>N</i>-vinyl-1,5-disubstituted 1,2,3-triazoles are reported using azidosugars as well as vinyl sulfone-modified carbohydrates for the first time. Selected 5-vinyl-triazoles afforded 1,2,3-triazole-fused polycyclic compounds.