1.1: BuLi; 2,2,6,6-tetramethylpiperidine / tetrahydrofuran; hexane / 0.67 h / -75 - -55 °C 1.2: 71 percent / hexachloroethane / tetrahydrofuran; hexane / -55 - 20 °C 2.1: Amberlyst(R) IR-200 / methanol / 0.25 h / 20 °C View Scheme