1: isopentyl nitrite / acetonitrile / 50 - 70 °C 2: N-ethyl-N,N-diisopropylamine / dichloromethane / 25 - 35 °C 3: lithium borohydride / tetrahydrofuran / 0 - 30 °C 4: hydrogenchloride; water / methanol / 25 - 30 °C View Scheme