1: 85 percent / tetrahydrofuran / 5 - 20 °C 2: DDQ / dioxane / 1 h 3: 19.88 g / Et3N / CH2Cl2 View Scheme

1: DDQ / dioxane / 1 h 2: 19.88 g / Et3N / CH2Cl2 View Scheme

triethylamine in dichloromethane

1: phenyltrimethylammonium tribromide / 1,2-dimethoxy-ethane; CH2Cl2 / 1 h / 40 - 45 °C 2: 18.43 g / Et3N / ethyl acetate / 1.5 h / 20 °C 3: 82 percent / PhPOCl2 / acetonitrile / 2.5 h / Heating 4: 96 percent / aq. NaOH / ethanol / 2 h / 65 - 70 °C View Scheme