1: 94 percent / Na2Cr2O7, conc. H2SO4 / diethyl ether; H2O / 2 h / 25 °C 2: 77 percent / dimethylsulfoxide / 70 °C 3: 88 percent / HCl / 12 h / 4 °C 4: 24 percent / NaBH4 / ethanol / 16 h / 40 °C 5: 98 percent / 2 N KOH / methanol / 50 °C View Scheme

1: 56 percent / dimethylsulfoxide / 2.5 h / 100 °C 2: 99 percent / HCl / diethyl ether / 17 h / -5 °C 3: 80 percent / 0.2 N HCl / diethyl ether / 17 h / Ambient temperature 4: 98 percent / 20percent diisobutyl aluminium hydride / toluene; hexane / 2 h / -40 °C 5: 99 percent / p-toluenesulfonic acid, molecular sieve 4 Angstroem / diethyl ether; petroleum ether / 1 h / Ambient temperature 6: 80 percent / HCl / diethyl ether View Scheme