1,3-dibromo-5,5-dimethyl-hydantoin; potassium iodide; sodium hydroxide in water; isopropyl alcohol; acetonitrile T=0 - 4°C; 1 h;

1: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / 2 h / |Reflux 2: tetrahydrofuran / 20 °C / |Inert atmosphere 3: potassium iodide; sodium hydroxide; 1,3-dibromo-5,5-dimethyl-hydantoin / isopropyl alcohol; water; acetonitrile / 1 h / 0 - 4 °C View Scheme

1: tetrahydrofuran / 20 °C / |Inert atmosphere 2: potassium iodide; sodium hydroxide; 1,3-dibromo-5,5-dimethyl-hydantoin / isopropyl alcohol; water; acetonitrile / 1 h / 0 - 4 °C View Scheme