1,3-dibromo-5,5-dimethyl-hydantoin; water in acetonitrile T=25°C; pH=5.0 - 6.5;

1: lithium diisopropylamide / tetrahydrofuran; heptane; ethylbenzene / 1.25 h / cooling 2: hydrochloric acid / various solvents / 1 h / 0 - 23 °C 3: 1,3-dibromo-5,5-dimethylhydantoin; H2O / acetonitrile / 25 °C / pH 5.0 - 6.5 View Scheme

ammonia in dichloromethane 1 h; Yield given;

1: 1) 10M NaOH 2) 30percent aq. H2O2 / 1) 70 deg C, 60 min 2) 70 deg C, 60 min 2: 1) 48percent HBr, NaNO2 2) CuBr / 1) water, 1 h, 0 deg C 2) a) 30 min, r.t. b) 90 min, 70 deg C 3: SOCl2 / CH2Cl2 / 1 h / Heating 4: NH3-gas / CH2Cl2 / 1 h View Scheme

1: 96 percent / Na2SO4, NH2OH*HCl, conc. HCl / H2O / 0.17 h / Heating 2: 55 percent / conc. H2SO4 / 0.75 h / 70 °C 3: 1) 10M NaOH 2) 30percent aq. H2O2 / 1) 70 deg C, 60 min 2) 70 deg C, 60 min 4: 1) 48percent HBr, NaNO2 2) CuBr / 1) water, 1 h, 0 deg C 2) a) 30 min, r.t. b) 90 min, 70 deg C 5: SOCl2 / CH2Cl2 / 1 h / Heating 6: NH3-gas / CH2Cl2 / 1 h View Scheme

1: 55 percent / conc. H2SO4 / 0.75 h / 70 °C 2: 1) 10M NaOH 2) 30percent aq. H2O2 / 1) 70 deg C, 60 min 2) 70 deg C, 60 min 3: 1) 48percent HBr, NaNO2 2) CuBr / 1) water, 1 h, 0 deg C 2) a) 30 min, r.t. b) 90 min, 70 deg C 4: SOCl2 / CH2Cl2 / 1 h / Heating 5: NH3-gas / CH2Cl2 / 1 h View Scheme

1: 1) 48percent HBr, NaNO2 2) CuBr / 1) water, 1 h, 0 deg C 2) a) 30 min, r.t. b) 90 min, 70 deg C 2: SOCl2 / CH2Cl2 / 1 h / Heating 3: NH3-gas / CH2Cl2 / 1 h View Scheme

1: SOCl2 / CH2Cl2 / 1 h / Heating 2: NH3-gas / CH2Cl2 / 1 h View Scheme

sodium hydroxide; bromine 1) 4 h, 0 deg C 2) 3 h, 60 deg C;