1.1: 78 percent / potassium trimethylsilanolate / CH2Cl2; acetonitrile / 1 h / 20 °C 2.1: sodium iodide / butan-2-one / 20 °C 3.1: potassium trimethylsilanolate / CH2Cl2; acetonitrile / 1 h / -10 °C 3.2: 0.90 g / CH2Cl2; acetonitrile / 5 h / -10 - 20 °C 4.1: trifluoroacetic acid; anisole / CH2Cl2 / 0.25 h / cooling View Scheme

1.1: sodium iodide / butan-2-one / 20 °C 2.1: potassium trimethylsilanolate / CH2Cl2; acetonitrile / 1 h / -10 °C 2.2: 0.90 g / CH2Cl2; acetonitrile / 5 h / -10 - 20 °C 3.1: trifluoroacetic acid; anisole / CH2Cl2 / 0.25 h / cooling View Scheme

N,N'-bis-(trimethylsilyl)-urea; NH4Br 1.) CH2Cl2, reflux, 1.5 h, 2.) CH2Cl2, -10 deg C, 1.5 h; Yield given. Multistep reaction;