Synthesis of Trifluoromethyl-Containing Imidazolidine-2-Thiones and Their Reactions with Urea, 2-Aminoethanol and 2-Aminophenol

The reaction of perfluorobiacetyl with thiourea, -methyl- and -phenylthiourea in acetonitrile afforded -, -isomers of 4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thione and 1-methyl(phenyl)-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thiones in 92–95% yield. The interaction of 4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thione with 2-aminoethanol (2-AE) affords thioxoimidazothiazolone, and the expected condensation product, thioimidazooxazine, is obtained as a minor product. An unusual reaction route of -methylimidazolidine-2-thione with 2-AE was found, leading to thioxohydantoins: 5-(2-hydroxyethyl)amino-3-methyl-2-thioxo-5-(trifluoromethyl)imidazolidin-4-one and 5-hydroxy-3-methyl-2-thioxo-5-(trifluoromethyl)imidazolidin-4-one. The reaction of -methylimidazolidine-2-thione with urea yields a condensation product of a different type, -methylthioxoimidazooxolone, instead of the supposed thioglycoluril, as well as -methyltrifluoromethylthioxohydantoin. Heating 1-phenyl-4,5-dihydroxy-4,5-bis(trifluoromethyl)imidazolidine-2-thione with urea, 2-AE, and 2-aminophenol in dimethylacetamide yields an intramolecular rearrangement product, -phenylbis(trifluoromethyl)thioxohydantoin.