Sulfur Glycosylation Reactions Involving 3-Allyl-2-Thiohydantoin Nucleoside Bases as Potential Antiviral and Antitumor Agents

3-Allyl-5-(Z)-arylidene-2-thiohydantoins 8a-f were synthesized from the direct condensation of the aromatic aldehydes 7a–f with 3-allyl-2-thiohydantoin (6), which in turn was prepared from the reaction of glycine and allyl isothiocyanate. The alkylation of 8a–f with alkyl bromides 9a, b gave 3allyl-5-(Z)-arylidene-2-(alkylmercapto)hydantoins 1a–1, S-Glycosylation and S-ribosylation took place on the reaction of 8a–f with pyranosyl bromides 11a, b and furanosyl bromide (15) under anhydrous alkaline conditions. The S-nucleoside structure, and not that of the N-nucleoside isomer, has been selected for the products. This structure has been confirmed from a model study of the coupling of 8a with α-D-glucose pentaacetate (13) and α-D-ribose tetrabenzoate (16) under Lewis acid conditions. The compounds do not display any antiviral and antitumoral activity.