Diastereoselective cycloaddition of isatin azomethine ylides to 5-arylidene-2-thiohydantoins bearing 3-positioned chiral substituent

1,3-Dipolar cycloaddition of azomethine ylide, generated from isatin and sarcosine, with 5-arylidene-2-thiohydantoins equipped with various chiral substituents at the N³ atom occurs diastereoselectively. The highest selectivity with dr = 5 : 1 was observed for the 2-thiohydantoin bearing 1,2-diphenylethyl substituent.