Reaction of 1,2-trans-glycosyl acetates with thiourea: a new entry to 1-thiosugars

The reaction of 1,2-trans-glycosyl acetates with thiourea under boron trifluoride etherate catalysis affording acetylated S-glycosyl isothiourea derivatives is described. The isothiourea derivatives obtained can be readily transformed into the desired 1-thiosugar derivative by reaction with triethylamine and subsequent alkylation or acylation of the in situ formed 1-thioaldose.