1: 87 percent / 0.2 M NaOEt / ethanol / 3 h / 0 °C 2: 90 percent / imidazole / dimethylformamide / 24 h 3: 93 percent / bis<2,2,2-trifluoro-1-phenyl-1-(trifluoromethyl)ethoxy>diphenylsulfurane / CCl4 / 70 h / Ambient temperature 4: 99 percent / diisobutylaluminium hydride / toluene / 1 h / -78 °C 6: 85 percent / n-butyl lithium / hexane; tetrahydrofuran / a) -78 deg C, 30 min, b) -70 deg C, 2 h, c) to r.t., 2 h 7: 86 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 1 h / Ambient temperature View Scheme