O-Tritylhydroxylamine

31938-10-0

31938-11-1

The general procedure for the synthesis of O-tritylhydroxylamine from N-trityloxyphthalimide was as follows: triethylamine (6.0 mL, 43.1 mmol) was added slowly and dropwise over 5 min to dichloromethane (55 mL) containing N-hydroxyphthalimide (6.42 g, 39.4 mmol) and triphthaloyl chloride (10.01 g, 35.8 mmol) in a in a stirred solution. The reaction mixture was stirred continuously for 1 h at room temperature and then poured into water (100 mL) to terminate the reaction. The organic layer was separated, washed sequentially with water (2 x 100 mL) and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure to afford N-(triphenylmethoxy)phthalimide (white foamy solid, 15.54 g). The intermediate was dissolved directly in a solvent mixture of chloroform (320 mL) and methanol (32 mL) without further purification, followed by slow dropwise addition of hydrazine hydrate (5.2 mL, 165.5 mmol). The reaction mixture was stirred for 2 h and poured into water (400 mL). The organic layer was separated, washed with water (2 x 300 mL) and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (silica gel 100 g, eluent: hexane-ethyl acetate, 9:1, ca. 1 L) to afford the target product, O-trityl hydroxylamine (8.92 g, 90% yield, based on triphthaloyl chloride calculations): white crystals with melting point of 85-86 °C (recrystallized from hexane); 1H NMR (400 MHz, CDCl3) δ. 7.47-7.43 (m, 6H, aromatic H), 7.37-7.26 (m, 9H, aromatic H), 4.95 (br s, 2H, NH); 13C NMR (100 MHz, CDCl3) δ: 143.2, 128.8, 127.8, 127.2, 90.8.