1.1: pyridine / CH2Cl2 / 20 °C 2.1: LiBr / acetone / Heating 3.1: sodium sulfide nonahydrate / ethanol / Heating 4.1: N-chlorosuccinimide / CCl4 / 3 h / Heating 4.2: 20 percent / m-chloroperbenzoic acid / CH2Cl2 / 18 h / 20 °C 5.1: 66 percent / potassium tert-butoxide / tetrahydrofuran; dimethylsulfoxide / 0.17 h / 20 °C View Scheme