pyridine; hydroxylamine-o-sulphonic acid in methanol; ethanol 0.5 h; Ambient temperature;

1: 89 percent / 20 h / Heating 2: 1.) Phosphorus oxychloride, 2.) Sodium perchlorate monohydrate / 1.) anhydr. Dichloromethane, room temp., 20 min; 0 deg C, 10 min, 2.) Dichloromethane/water, 0 deg C, 20 min 3: 73 percent / Sodium sulfide nonahydrate / dimethylformamide; H2O / 2 h / Ambient temperature 4: 61 percent / Pyridine, Hydroxylamine-O-sulfonic acid / ethanol; methanol / 0.5 h / Ambient temperature View Scheme

1: 73 percent / Sodium sulfide nonahydrate / dimethylformamide; H2O / 2 h / Ambient temperature 2: 61 percent / Pyridine, Hydroxylamine-O-sulfonic acid / ethanol; methanol / 0.5 h / Ambient temperature View Scheme

1: 1.) Phosphorus oxychloride, 2.) Sodium perchlorate monohydrate / 1.) anhydr. Dichloromethane, room temp., 20 min; 0 deg C, 10 min, 2.) Dichloromethane/water, 0 deg C, 20 min 2: 73 percent / Sodium sulfide nonahydrate / dimethylformamide; H2O / 2 h / Ambient temperature 3: 61 percent / Pyridine, Hydroxylamine-O-sulfonic acid / ethanol; methanol / 0.5 h / Ambient temperature View Scheme