Utilization of Dipotassium Salt of Galactaric Acid Bis(Hydrazidocarbodithioic Acid) As a Synthone for Double-Headed 1,3,4-Thiadiazoline, 1,3,4-Oxadiazoline and 1,2,4-Triazoline Acyclo C-Nucleosides

Abstract

Condensation of galactaric acid bis hydrazide (1) with carbon disulfide in the presence of ethanolic potassium hydroxide gave the dipotassium salt of galactaric acid bis (hydrazidocarbodithioic acid) (2). Heterocyclization of the key compound 2 produced three different types of double headed acyclo C-nucleosides: acid-catalyzed dehydrative cyclization afforded the 5-thioxo-1,3,4-thiadiazoline 3, base-catalyzed dehydrosulfurative cyclization gave the 5-thioxo-1,3,4-oxadiazoline 5, and condensative cyclization with concomitant dehydrosulfuration and dehydration with different nitrogen nucleophiles yielded the 5-thioxo-1,2,4-triazolines 7 and 9a, b. Acetylation of the prepared acyclo C-nucleosides 3, 5, 7 and 9a, b with acetic anhydride in the presence of pyridine at ambient temperature caused acetylation of the sugar hydroxyls as well as heterocyclo imino protons to give the tetra-O-acetates 4, 6, and 10a, b, respectively. Representative members of the prepared compounds were tested for antimicrobial activity.