Sodium hydride → 3-(3-{4-[(6-Hydroxyhexyl)oxy]butyl}phenyl)imidazolidine-2,4-dione

A solution of ethyl N-({[3-(4-{[6-(acetyloxy)hexyl]oxy}butyl)phenyl]amino}-carbonyl)glycinate (2.967 g) in ethanol (30 ml) was treated under nitrogen with sodium hydride (60% oil dispersion; 280 mg) and the mixture was stirred for 18 h. The solvent was removed under reduced pressure, the residue was dissolved in acetic acid (10 ml) and conc. HBr (1 ml) and the mixture was heated to 75° C. for 1 h. The solvent was removed under reduced pressure, the residue was partitioned between EtOAc and brine. The organic solution was washed with brine, dried and evaporated to dryness. The residue was dissolved in MeOH (30 ml), SOCl2 (0.5 ml) was added, and the solution was stirred for 2 h. The solvent was removed under reduced pressure to give the title compound (2.67 g) ES+ve 349 (MH)+.