1: 81 percent / CuSO4, conc. H2SO4 / 24 h / Ambient temperature 2: 87 percent / pyridinium chlorochromate / CH2Cl2 / 1 h 3: 88 percent / diisopropylamine, butyllithium / tetrahydrofuran; hexane / 1.5 h / -78 °C 4: 65 percent / HCl / methanol / 1.5 h / Heating 5: 84 percent / methanesulphonyl chloride / pyridine / 24 h / Ambient temperature 6: 90 percent / trifluoroacetic acid, water / 1 h / 50 °C View Scheme