1: phosphorus tribromide / dichloromethane / 1.08 h / 0 - 20 °C / Inert atmosphere 2: urea; sodium nitrite / N,N-dimethyl-formamide / -10 °C / Inert atmosphere 3: acetic acid / methanol / 2.5 h / 20 °C / Inert atmosphere 4: 1,8-diazabicyclo[5.4.0]undec-7-ene / tetrahydrofuran; isopropyl alcohol / 0 - 20 °C / Inert atmosphere 5: lithium aluminium tetrahydride / tetrahydrofuran / 1 h / 0 °C / Inert atmosphere 6: dihydrogen peroxide; sodium hydrogencarbonate / methanol / 20 °C / Inert atmosphere View Scheme