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