Facile synthesis of 5-arylidene thiohydantoin by sequential sulfonylation/desulfination reaction.

The sequential sulfonylation/desulfination reactions of 5-benzylthiohydantoin with excess arylsulfonyl chlorides in the presence of triethylamine have been developed to afford a wide range of 5-arylidene thiohydantoin derivatives in moderate to excellent yields. A plausible sulfonylation/desulfination mechanism was proposed. The bioassay showed that these compounds exhibit certain fungicidal activities with the 71.9% inhibition rate of 2K against B. cinerea, and 57.6% inhibition rate of 2m against A. solani, respectively.