Preparation of 3,5-bis-(β-d-glycopyranosyl)-1,2,4-thiadiazoles from C-(β-d-glycopyranosyl)thioformamides

Acylated C-glycopyranosyl thioformamides of d-gluco, d-galacto, and d-xylo configuration were obtained by treating the corresponding glycosyl cyanides with hydrogen sulfide in the presence of triethylamine. The thioformamides gave 3,5-bis-(β-d-glycopyranosyl)-1,2,4-thiadiazoles in reactions with potassium bromate and sodium dithionite in dichloromethane–water biphasic solvent mixture. Deprotected derivatives were prepared by Zemplén deacylation.