1: 1.) sodium amide, 2.) hexamethylphosphoramide / 1.) THF, 50 deg C, 1.5 h, 2.) room temperature, 1 h 2: toluene-p-sulphonic acid / methanol / 0.5 h / 70 °C 3: 91 percent / cerium(IV) ammonium nitrate / acetonitrile; H2O / 0.67 h / 0 - 2 °C View Scheme

1: 1.) sodium amide, 2.) hexamethylphosphoramide / 1.) THF, 50 deg C, 1.5 h, 2.) room temperature, 1 h 2: toluene-p-sulphonic acid / methanol / 0.5 h / 70 °C 3: 91 percent / pyridine-2,6-dicarboxylic acid, cerium(IV) ammonium nitrate / acetonitrile; H2O / 0.5 h / 0 - 2 °C View Scheme

1: 1.) sodium amide, 2.) hexamethylphosphoramide / 1.) THF, 50 deg C, 1.5 h, 2.) room temperature, 1 h 2: toluene-p-sulphonic acid / methanol / 0.5 h / 70 °C View Scheme