Synthesis 5-(pyrazolin-3-ylmethylidene)-2-thiohydantoins and 2-alkylsulfanyl-5-(pyrazolin-3-ylmethylidene)-3,5-dihydro-4H-imidazol-4-ones

Regio‐ and Chemoselectivity of Tandem N‐Ketoalkylation/Cyclization of 2‐Thioxoimidazoline‐4‐One

“…[24] N3-Substituted thiohydantoins react with alkyl halides or phenacyl bromide in aqueous solution of sodium hydroxide and ethanol affording the target products in good yield. [27][28][29][30] When using halogen-containing compounds (chloroacetonitrile, alkyl bromoacetates, allyl bromide, propyl bromide), the French authors have shown a low reactivity of some chloro-and bromoalkanes, that impelled them to add one equivalent of KI to the reaction mixture. [31] To the best of our knowledge, prior to the present study, there had been no report on the alkylation of thiohydantoin or its derivatives with α-iodoketones that might lead to the corresponding salts.…”

“…The catalytic chemoselective S‐alkylation of 5‐substituted thiohydantoins with trimethyl or triethyl orthoformates was shown to be accompanied by N‐acetylation [24] . N3‐Substituted thiohydantoins react with alkyl halides or phenacyl bromide in aqueous solution of sodium hydroxide and ethanol affording the target products in good yield [27–30] . When using halogen‐containing compounds (chloroacetonitrile, alkyl bromoacetates, allyl bromide, propyl bromide), the French authors have shown a low reactivity of some chloro‐ and bromoalkanes, that impelled them to add one equivalent of KI to the reaction mixture [31] …”