thionyl chloride in benzene 3 h; Reflux;

1: 2.65 g / cesium carbonate / dimethylformamide / 18 h / 20 °C 2: 2.15 g / TFA / CH2Cl2 / 1.5 h / 0 °C 3: 2.13 g / thionyl chloride / 2 h / Heating View Scheme

1: 2.15 g / TFA / CH2Cl2 / 1.5 h / 0 °C 2: 2.13 g / thionyl chloride / 2 h / Heating View Scheme

1: thionyl chloride / 2 h / Heating 2: hydroxylamine hydrochloride; N-methylmorpholine / tetrahydrofuran; H2O / 2.5 h 3: 2.65 g / cesium carbonate / dimethylformamide / 18 h / 20 °C 4: 2.15 g / TFA / CH2Cl2 / 1.5 h / 0 °C 5: 2.13 g / thionyl chloride / 2 h / Heating View Scheme

1.1: sodium hydroxide / tetrahydrofuran / 2 h / |Reflux 1.2: pH 1 2.1: thionyl chloride / benzene / 3 h / |Reflux View Scheme