1: 65.7 percent / sodium hydride, cuprous iodide / dimethylformamide / 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 12 h 2: 88.1 percent / manganese dioxide / CH2Cl2 / 72 h / Ambient temperature 3: 71.9 percent / Claisen's alkali / 0.5 h / Heating View Scheme

bromine in acetic acid 2 h; Ambient temperature;

copper(l) iodide; sodium hydride in N,N-dimethyl-formamide 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 12 h;