Stereoselective Synthesis of 5-((Z)-Heteroarylmethylidene) Substituted Hydantoins and Thiohydantoins as Aplysinopsin Analogs*

3-Substituted 5-[(Z)-heteroarylmethylidene]imidazolidine-2,4-dione and 5-[(Z)-heteroarylmethylidene]-2-thiooxoimidazolidin-4-one derivatives were prepared stereoselectively by coupling of 5-(dimethylamino)methylidene substituted hydantoin and thiohydantoin derivatives with carbocyclic and heterocyclic C-nucleophiles. Configuration around the exocyclic C=C double bond was determined by NMR, using NOESY and 2D HMBC techniques.