Synthesis of Trifluoromethyl-Substituted Imidazolidine-2-thiones and Their Reactions with Urea, 2-Aminoethanol, and 2-Aminophenol

Perfluorobiacetyl reacted with thiourea, N-methylthiourea, and N-phenylthiourea in acetonitrile to give 92–95% of cis/trans-isomeric 4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thione and 1-methyl­(phenyl)-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thiones. The reaction of 4,5-dihy­droxy-4,5-bis(trifluoromethyl)imidazolidine-2-thione with 2-aminoethanol produced sulfanylideneimidazothiazolone, whereas the expected imidazooxazinethione was formed as a minor product. An unusual pathway was observed in the reaction of N-methylimidazolidine-2-thione with 2-aminoethanol, which afforded thiohydantoins, 5-[(2-hydroxyethyl)amino]-3-methyl-2-sulfanylidene-5-(trifluoromethyl)imidazolidin-4-one and 5-hydroxy-3-methyl-2-sulfanylidene-5-(trifluoromethyl)imidazolidin-4-one. N-Methylsulfanylideneimidazooxazolone and N-methyl(trifluoromethyl)thiohydantoin were formed instead of the expected thioglycoluril derivative in the reaction of N-methylimidazolidine-2-thione with urea. Heating of 4,5-dihydroxy-1-phenyl-4,5-bis(tri­fluoro­methyl)imidazolidine-2-thione with urea, 2-aminoethanol, or 2-aminophenol in N,N-dimethylacetamide led to the formation of intramolecular rearrangement product, N-phenyl-bis(trifluoromethyl)thiohydantoin.