1: chlorosulfonic acid / acetonitrile / 1 h / Cooling with ice 2: potassium hydroxide / water / 3.5 h / 80 °C View Scheme

1: trifluoroacetic acid / dichloromethane / 24 h 2: sodium tetrahydroborate; iodine / tetrahydrofuran / 19 h / 0 °C / |Reflux 3: triethylamine / dimethyl sulfoxide / 2 h / 100 °C / |Irradiation View Scheme

1: sodium tetrahydroborate; iodine / tetrahydrofuran / 19 h / 0 °C / |Reflux 2: triethylamine / dimethyl sulfoxide / 2 h / 100 °C / |Irradiation View Scheme

1: potassium hydroxide; (S)-N-(4-bromobenzyl)-N,N,3,3-tetramethyl-2-(3-(4-nitrophenyl)thioureido)butan-1-ammonium acetate / dichloromethane / 1 h / -30 °C / |Inert atmosphere 2: sodium nitrite; acetic acid / dimethyl sulfoxide / 24 h / 40 °C 3: trifluoroacetic acid / dichloromethane / 24 h 4: sodium tetrahydroborate; iodine / tetrahydrofuran / 19 h / 0 °C / |Reflux 5: triethylamine / dimethyl sulfoxide / 2 h / 100 °C / |Irradiation View Scheme