1: triethylamine / ethanol / 40 - 80 °C / Inert atmosphere 2: hydrogenchloride; water / methanol / 35 °C 3: sodium nitrite / water; methanol / 0 - 5 °C 4: N-ethyl-N,N-diisopropylamine / acetonitrile / 25 - 35 °C View Scheme