Chemical Reactivity of 2-Thiohydantoin Derivatives

Treatment of 5-arylazo-2-thiohydantoins (2 a-c) with formaldehyde and the appropriate amine in ethyl alcohol led to the formation of the corresponding Mannich bases 3a-i. 2 a-c reacted with methyl bromoacetate and/or chloroacetic acid to give the esters 5 a-c and/or the free acids 5d-f, respectively. 5e also obtained by treating 5 b with aqueous sodium hydroxide (2%). 5 a-c were cyclised with acetic anhydride to give the bicyclic products 6 a-c. 5-Arylidene-2-thiohydantoins (7 a-e) reacted with acrylonitrile in pyridine to give 5-arylidene-3-β-cyano-ethyl-2-thiohydantoins (8a-e). 8 a-c were hydrolysed with a mixture of acetic-hydrochloric acid to give the corresponding acids 8f-h. Compounds 8a, b, d were alkylated with alkyl halides to give 10 a-e which when hydrolysed with acids gave compounds 13 a-c.