1: NaBH4 / tetrahydrofuran; methanol / 1 h / -15 °C 2: Et3N / tetrahydrofuran / 14 h / 20 °C 3: 2.53 g / 1,8-diazabicyclo[5,4,0]undec-7-ene / tetrahydrofuran / 0.17 h / Heating 4: 100 percent / aq. HCl / ethyl acetate / 0.5 h / 80 °C View Scheme