1: n-Bu4NF / tetrahydrofuran / 0.25 h / 0 °C 2: 75percent aq. CH3COOH / tetrahydrofuran / 0 - 5 °C 3: 68 percent / diethyl cyanophosphonate, Et3N / dimethylformamide / 0.5 h / 0 °C 4: 86 percent / (COCl)2, (CH3)2SO / CH2Cl2 / 0.33 h / -78 °C 5: 69 percent / lithium bis(trimethylsilyl)amide / tetrahydrofuran / 2.5 h / 0 °C 6: 100 percent / 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), H2O / CH2Cl2 / 0.5 h / Ambient temperature 7: 64 percent / CF3COOH / 2.5 h / Ambient temperature View Scheme