Synthesis of ν-triazole derivatives from anomeric sugar diazides

Staudinger reaction of acetylated glycopyranosylidene 1,1-diazides led to resonance-stabilized iminophosphoranes (phosphinimines) of 6,7-dihydro[3,4-d]-1,2,3-triazole. This unprecedented transformation involves β-elimination of acetic acid and cycloaddition of azide anion to the resulting C-2 double bond. Transformation of the new fused heterocyclic iminophosphoranes on treatment with aqueous ethanolic ammonia gives carboxamidine derivatives of ν-triazole bearing a chiral trihydroxypropyl side-chain. Crystal structure of 5-(d-erythro-1′,2′,3′-trihydroxypropyl)-1,2,3-triazole-4-carboxamidine was established by X-ray crystallography.