1: triethylamine / ethanol / 50 - 60 °C / Inert atmosphere 2: hydrogenchloride; water / methanol / 35 °C 3: isopentyl nitrite / acetonitrile / 30 - 60 °C 4: N-ethyl-N,N-diisopropylamine / acetonitrile / 25 - 35 °C 5: lithium borohydride / tetrahydrofuran / -10 - 20 °C View Scheme