1.1: lithium diisopropylamide / tetrahydrofuran; hexane / -78 - 20 °C 1.2: 115 mg / lithium tetrachlorocuprate(II) / tetrahydrofuran; hexane / 13 h / 20 °C 2.1: 100 percent / 0.25 h / 200 °C 3.1: 83 percent / tetrabutylammonium sulfate; sodium hydroxide / benzene; H2O / 24 h / 40 °C 4.1: phosphorus oxychloride / toluene / Heating 4.2: 78 percent / sodium hydroxide / tetrahydrofuran / 20 °C View Scheme