1.1: 50.7 percent / ZnCl2 / 108 h / 20 °C 2.1: molecular sieves 4 Angstroem / 1,2-dichloro-ethane / 1.5 h / 20 °C 2.2: 66.2 percent / trimethylsilyl triflate / 1,2-dichloro-ethane / 0.25 h / -18 °C 3.1: acetic acid; H2O / 45 °C 4.1: pyridine 5.1: 89.7 percent / Na / methanol / 1.5 h View Scheme