trifluoroacetic acid in dichloromethane T=20°C; 3 h; Cooling with ice;

lithium hydroxide hydrate in tetrahydrofuran; methanol; water 24 h; Inert atmosphere;

1: tetrakis(triphenylphosphine) palladium(0); sodium carbonate / 1,4-dioxane / 90 °C / Inert atmosphere 2: lithium hydroxide hydrate / tetrahydrofuran; methanol; water / 24 h / Inert atmosphere View Scheme

1.1: oxalyl dichloride; N,N-dimethyl-formamide / dichloromethane / 2 h / 20 °C 2.1: pyridine / 21 h / 20 °C 3.1: tetrakis(triphenylphosphine) palladium(0) / N,N-dimethyl-formamide / 0.17 h / 20 °C 3.2: 4 h / 120 °C 4.1: trifluoroacetic acid / dichloromethane / 3 h / 20 °C / Cooling with ice View Scheme

1.1: pyridine / 21 h / 20 °C 2.1: tetrakis(triphenylphosphine) palladium(0) / N,N-dimethyl-formamide / 0.17 h / 20 °C 2.2: 4 h / 120 °C 3.1: trifluoroacetic acid / dichloromethane / 3 h / 20 °C / Cooling with ice View Scheme

1.1: tetrakis(triphenylphosphine) palladium(0) / N,N-dimethyl-formamide / 0.17 h / 20 °C 1.2: 4 h / 120 °C 2.1: trifluoroacetic acid / dichloromethane / 3 h / 20 °C / Cooling with ice View Scheme