Abstract
1,4-Disubstituted thiosemicarbazides (5a-c) were prepared by the reaction of the isothiocyanate (3) with isomeric pyridinecaboxylic acid hydrazides (4a-c). Base catalyzed cyclization of the thiosemicarbazides furnished substituted 1,2,4-triazol-3-thiones (6a-c) in good yields. These were subjected to coupling with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide in presence of mercuric cyanide leading to three new nucleosides (7a-c).