1,2-Dibromobutane → Tert-butyl 2,3-dihydro-1,4-benzoxazine-4-carboxylate

Participants

Reaction Steps

A solution of dry acetone (100 mL) containing N-(tertbutoxycarbonyl)-2-aminophenol (0.722 g, 3.69 mmol), potassium carbonate (10.2 g, 73.8 mmol) and 1,2-dibromobutane (2.54 mL, 29.6 mmol) was refluxed for 18 h. The reaction was monitored by TLC (petrol/ether 8/2). After cooling, the mixture was filtered through celite. After concentration and hydrolysis, the aqueous layer was extracted with EtOAc (3×40 mL), dried over MgSO4 and the solvent was removed under reduce pressure. The crude product was purified by flash chromatography on silica gel (petrol/EtOAc 95/5) to yield the title compound as a white solid (0.70 g, 82%). m.p=78-79° C.; Rf=0.44(petrol/ether 8/2); LCMS m/z 236 ([M+1]+); 1H NMR (300 MHz, CDCl3): δ 1.59 (9H, s); 3.87 (4H, m); 4.26 (4H, m); 6.86-7.02 (4H, m); 13C NMR (75 MHz, CDCl3): δ 27.4 (3C); 41.1; 64.6(2C); 80.6 (2C); 116.0; 119.2; 122.6; 123.4; 125.2; 144.9; 151.6. IR (film): 2975; 1696; 1494; 1143 cm−1.

Provenance & Evidence