4-Thiohydantoin and 1-phenyl-4-thiohydantoin reacted with aromatic aldehydes to give the corresponding 5-arylidene-4-thiohydantoin (1 a-h). la was obtained also from 5-benzylidene hydantoin and phosphorous pentasulphide. Grignard reagents added to the lateral double bond of (1 a-c) to give after hydrolysis the colorless products 3. Treatment of (1a, b) with alkylating agents gave the corresponding alkylmercapto derivatives (4 a-h). Also (4a, e) were obtained by the action of ethereal diazomethane on (1a, b). By further methylation of (4 e) with diazomethane, a cyclopropane derivative could be isolated.

l-Phenyl-4-thiohydantoin, Alkylating Agents, Amines, Mannich Reaction l-Phenyl-4-thiohydantoin reacted with aryldiazonium salts to give the corresponding 5-arylazo-l-phenyl-4-thiohydantoin (la-f). On alkylation of la,b,f with different alkyl halides, the corresponding 4-alkylmercapto derivatives (2 a-f) were obtained. 2 a was hydrolysed with a mixture of ethanol-hydrochloric acid to give 5-phenylazo-l-phenylhydantoin (3). Treatment of 2a,d with amines gave the products 4a-h. 4a when refluxed with a mixture of acetic-hydrochloric acid, the product 3 was obtained. la,b reacted with formaldehyde and appropriate amine to give the corresponding Mannich bases 5 a-k. Also l-phenyl-4-thiohydantoin when exposed to the Mannich reaction, 6 a-e were obtained. 6 a when treated with benzenediazonium chloride, the colour substance 5 a was separated.

Die Titelverbindung (I) reagiert mit den Arendiazoniumsalzen (II) zu den Azoderivaten (III), von denen (IIIa) und (IIIb) mit Alkylhalogeniden (IV) zu den Mercaptoverbindungen (V) umgesetzt werden.

Cyclisierungen der Titelverbindungen (I) in siedendem Acetanhydrid liefern die Imidazothiazole (II).

Aus den 4‐Thiohydantoinen (I) werden die kondensierten Heterocyclen (IV) hergestellt, die mit Benzaldehyd (V), den Diazoniumsalzen (VII) und nach Mannich mit Formaldehyd (IX) und den Anilinen (X) umgesetzt werden.