trifluoroacetic acid in dichloromethane T=20°C; 2 h;

1.1: trifluoroacetic acid / dichloromethane / 2 h / 20 °C 2.1: sodium hydride / tetrahydrofuran / 20 h / 20 °C 3.1: sodium hydride / 1,4-dioxane / 1 h / |Reflux 3.2: 20 h / |Reflux View Scheme