Synthesis of fluorine containing N-heterocycles using oxides of terminal perfluoroolefins and urea

Abstract The reaction of octafluoro-1,2-epoxybutane ( 1 ) with urea in Me 2 SO, aqueous Me 2 SO, aqueous dioxane, aqueous acetonitrile and of hexadecafluoro-1,2-epoxyoctane ( 2 ) with urea in aqueous Me 2 SO gave perfluoroalkylhydantoins – 5-hydroxy-5-pentafluoroethylimidazolidine-2,4-dione ( 4a ) (yield 40–42%) and 5-hydroxy-5-tridecafluorohexylimidazolidine-2,4-dione ( 4b ) (yield 54%), respectively. Use of dioxane and acetonitrile in the reaction of oxiranes 1 , 2 with urea led to unexpected heterocyclic products – perfluoroalkyloxazoles 7a , b (yield 11–82%). Perfluoroalkyl containing allantoin – 5-tridecafluorohexyl-5-ureidoimidazolidine-2,4-dione ( 3b ) (yield 19%) and polyfluoroalkyl containing urea–(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoro-1-hydroxyheptyl)urea ( 6b ) (yield 46%) have been first obtained by the reaction of oxirane 2 with urea in Me 2 SO and aqueous Me 2 SO, respectively. The molecular and crystal structure of hydantoin 4a has been studied by X-ray crystallography.