potassium tert-butylate in tetrahydrofuran T=45°C; 1.5 h;

1: 72.3 percent / bromine / pyridine; CHCl3 / -40 °C 2: t-BuOK / tetrahydrofuran / 2 h / 45 - 50 °C 3: 96.2 percent / bromine / CCl4 / 75 °C 4: 93.6 percent / t-BuOK / tetrahydrofuran / 1.5 h / 45 °C View Scheme

n-butyllithium in tetrahydrofuran; hexane 1) 0.7 h, -78 deg C, 2) -78 deg C to room temperature, 2 h;