1.1: Mg / tetrahydrofuran / 1.5 h / Heating 1.2: 78 percent / tetrahydrofuran; benzene / 0 - 22 °C 2.1: 98 percent / KOH / ethanol / 24 h / Heating 3.1: Et3N; ethyl chloroformate / acetone / 0.5 h / -15 °C 3.2: 96 percent / NaN3 / acetone; H2O / 1.5 h / -15 °C 4.1: 96 percent / BBr3 / CH2Cl2 / 0 - 22 °C View Scheme