Trifluoroacetic acid → 3,4-Dihydro-2H-1,4-benzoxazine

Participants

Reaction Steps

To a solution of dichloromethane (10 mL) containing N-(tertbutoxycarbonyl)-2,3-dihydro-benzo[1,4]oxazine (0.438, 1.86 mmol) at 0° C. was added slowly trifluoroacetic acid (1.0 mL, 7.44 mmol). The reaction mixture was stirred at this temperature during 5 h, then the solvent was removed in vaccuo. The crude product was dissolved in EtOAc (15 mL) and washed successively with 10% Na2CO3 solution and water. The organic layer was dried over MgSO4 and the solvent was removed under reduce pressure. The title compound was obtained pure as brown oil (0.245 g, 98%). Rf=0.31 (petrol/ether 5/5); LCMS m/z 136 ([M+1]+); 1H NMR (300 MHz, CDCl3): δ 3.43 (4H, m); 3.54 (1H, s); 4.27 (4H, m); 6.60-6.82 (4H, m); 13C NMR (75 MHz, CDCl3): δ 43.4; 67.7; 118.1; 119.2; 121.3; 123.7; 136.1; 146.6. IR (film): 3375; 1498; 741 cm−1.

Provenance & Evidence