O-(Tetrahydro-2H-pyran-2-yl)hydroxylamine synthesis

110-87-2

6723-30-4

General procedure for the synthesis of O-(tetrahydro-2H-pyran-2-yl)hydroxylamine from 3,4-dihydro-2H-pyran: N-hydroxyphthalimide (10 g, 0.061 mol) and 3,4-dihydro-2H-pyran (6.1 g, 0.073 mol) were added to a 250 mL three-necked flask, and tetrahydrofuran (100 mL) was added to dissolve. Subsequently, p-toluenesulfonic acid (1.1 g, 6.1 mmol) was added to catalyze the reaction. The reaction was carried out at room temperature for 2 hours. Upon completion of the reaction, the tetrahydrofuran was removed by distillation under reduced pressure. Water (200 mL) was added to the residue and extracted with dichloromethane (3 x 200 mL). The organic phases were combined and washed sequentially with saturated aqueous NaHCO3 solution (3 x 200 mL) and saturated aqueous NaCl solution (200 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and evaporated to dryness to give a yellow-green solid (15.3 g). The resulting solid was transferred to a 1000 mL three-necked flask and ethanol (450 mL) was added and stirred to dissolve. 80% hydrazine hydrate (10.4 mL, 0.17 mol) was slowly added dropwise and the reaction was carried out for 1 hour at room temperature. The reaction solution was directly filtrated and the filtrate was evaporated to give the crude product (10.6 g). The crude product was dissolved with ethyl acetate (500 mL), mixed thoroughly and vacuum filtered to remove insoluble matter. The filtrate was washed with water (3×100 mL) and saturated NaCl aqueous solution (200 mL) sequentially, dried with anhydrous sodium sulfate and filtered, evaporated to dryness to obtain a light yellow oil. The oily material was dried under vacuum to give a yellow solid (5.39 g) with a melting point of 35-37 °C and a yield of 75.3%.