trifluoroacetic acid in dichloromethane T=0°C; 3 h;

1: lithium hydroxide hydrate / tetrahydrofuran; water / 5 h / 0 °C 2: trifluoroacetic acid / dichloromethane / 3 h / 0 °C View Scheme

1.1: 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 0.25 h / 0 °C 1.2: 24 h 2.1: lithium hydroxide hydrate / tetrahydrofuran; water / 5 h / 0 °C 3.1: trifluoroacetic acid / dichloromethane / 3 h / 0 °C View Scheme

1.1: 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 0.25 h / 0 °C 1.2: 24 h 2.1: lithium hydroxide hydrate / tetrahydrofuran; water / 5 h / 0 °C 3.1: trifluoroacetic acid / dichloromethane / 3 h / 0 °C View Scheme