1: 1.) LDA / 1.) THF, hexane, -78 deg C, 30 min, 2.) from -50 deg C to 20 deg C, overnight 2: oxalyl chloride / dimethylformamide; CH2Cl2 / 0.5 h 3: Et3N / CH2Cl2 / 10 - 15 °C 4: 58 percent / CF3CO2HF / 16 h / 20 °C View Scheme

1: 1.) LDA / 1.) THF, hexane, -78 deg C, 30 min, 2.) from -50 deg C to 20 deg C, overnight 2: oxalyl chloride / dimethylformamide; CH2Cl2 / 0.5 h 3: Et3N / CH2Cl2 / 10 - 15 °C 4: 58 percent / CF3CO2HF / 16 h / 20 °C 5: 22 percent / 2,6-lutidine / various solvent(s) / 18 h / 80 °C 6: 41 percent / 1 N aq. NaOH / 2 h View Scheme

1: 1.) LDA / 1.) THF, hexane, -78 deg C, 30 min, 2.) from -50 deg C to 20 deg C, overnight 2: oxalyl chloride / dimethylformamide; CH2Cl2 / 0.5 h 3: Et3N / CH2Cl2 / 10 - 15 °C 4: 58 percent / CF3CO2HF / 16 h / 20 °C 5: 22 percent / 2,6-lutidine / various solvent(s) / 18 h / 80 °C View Scheme