potassium carbonate in N,N-dimethyl-formamide T=100°C; 5 h;

1: 1.88 g / Et3N / toluene / 5 h / 90 °C 2: ethanol; diethyl ether / 3 h / 20 °C 3: 627 mg / K2CO3 / dimethylformamide / 5 h / 100 °C View Scheme

1: oxalyl chloride; DMF / CH2Cl2 / 24 h / 20 °C 2: 1.88 g / Et3N / toluene / 5 h / 90 °C 3: ethanol; diethyl ether / 3 h / 20 °C 4: 627 mg / K2CO3 / dimethylformamide / 5 h / 100 °C View Scheme

1: 61 percent / 1.0 N aq. NaOH / methanol / 3 h / Ambient temperature 2: oxalyl chloride, DMF / CH2Cl2 / 18 h / Ambient temperature 3: 1.) n-BuLi, 2,2'-bipyridyl / 1.) THF, hexane, from -20 deg C to -5 deg C, 2.) THF, hexane, -30 deg C, 2 h 4: acetic anhydride / 22 h / Heating 5: ethanol / 18 h / Ambient temperature 6: 81 percent / NaH / tetrahydrofuran / 18 h View Scheme

1: acetic anhydride / 22 h / Heating 2: ethanol / 18 h / Ambient temperature 3: 81 percent / NaH / tetrahydrofuran / 18 h View Scheme

1: ethanol / 18 h / Ambient temperature 2: 81 percent / NaH / tetrahydrofuran / 18 h View Scheme

1: ethanol; diethyl ether / 3 h / 20 °C 2: potassium carbonate / dimethylformamide / 5 h / 100 °C View Scheme

1: ethanol; diethyl ether / 3 h / 20 °C 2: 627 mg / K2CO3 / dimethylformamide / 5 h / 100 °C View Scheme

water; hydrogen bromide; acetic acid T=100°C;

sulfuric acid; acetic acid in water 2 h; Reflux;