1: sodium acetate / water / 4 h / 110 - 116 °C 2: hydrogenchloride / water; ethanol / 13 - 25 °C 3: trifluoroacetic acid / 1.5 h / 50 °C 4: N,N'-dimethyl-barbituric acid; triphenylphosphine; palladium diacetate / ethanol / 2 h / 35 °C / |Sealed tube; |Inert atmosphere View Scheme

1: sodium acetate / water / 4 h / 110 - 116 °C 2: hydrogenchloride / water; ethanol / 13 - 25 °C 3: trifluoroacetic acid / 1.5 h / 50 °C 4: N,N'-dimethyl-barbituric acid; triphenylphosphine; palladium diacetate / ethanol / 2 h / 35 °C / |Sealed tube; |Inert atmosphere 5: phosphoric acid / ethanol / 50 °C View Scheme