1: sodium ethylate; ethanol 2: aq.-ethanolic KOH-solution View Scheme

1: 1.) potassium metabisulfite / 1.) 50 deg C, water 2.) water, ether, 5 deg C, 6 h 2: stannous chloride dihydrate, cc. hydrogen chloride, acetic acid, hydrogen iodide / 3 h / Heating 3: 77 percent / cc. sulfuric acid / 12 h / Heating 4: sodium / toluene / 4 h / Heating View Scheme

1,8-diazabicyclo[5.4.0]undec-7-ene T=160°C; 3 h;

1: sodium ethylate; ethanol 2: aq.-ethanolic KOH-solution 3: chloroform; phosphorus (V)-chloride View Scheme