Lithiation of N'-arylureas derived from amino nitriles incorporating a (1R,2R)-2-aminocyclohexanol chiral auxiliary leads to diastereoselective migration of the aryl ring to the position α to the nitrile. The resulting N'-lithiated ureas undergo spontaneous cyclisation to iminohydantoins, which may be hydrolysed to give chiral 5,5-diarylhydantoins related to phenytoin, in enantioenriched form.