6-bromo-5-methyl-2H-benzo[b][1,4]oxazin-3(4H)-one → 6-Bromo-3,4-dihydro-5-methyl-2H-1,4-benzoxazine
Reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][C:8](=O)[NH:7][C:6]=2[C:12]=1[CH3:13]>O1CCCC1>[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH2:8][NH:7][C:6]=2[C:12]=1[CH3:13]Participants
3
Reactant 1
Product 1
Reagents, catalysts & solvents 1
Procedure
An ice cold mixture of 6-bromo-5-methyl-2H-1,4-benzoxazin-3(4H)-one (3.05 g, 12.59 mmol) in tetrahydrofuran (THF) (40 mL) was treated with borane tetrahydrofuran complex (1.0 M solution in tetrahydrofuran (18.88 mL, 18.88 mmol) and the mixture was stirred at ambient temperature for 150 minutes. The mixture was cooled to 0° C. and then quenched slowly with 1N NaOH (30 mL). The mixture was extracted with ethyl acetate, then washed with 1N NaOH, dried over sodium sulfate, filtered and then concentrated to a thick dark brown oil. The material was purified on silica gel (95:4:1 dichloromethane/methanol/ammonium hydroxide, gradient) to afford an off-white solid: 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 6.87 (d, J=8.6 Hz, 1 H), 6.57 (d, J=8.8 Hz, 1 H), 4.31-4.15 (m, 2 H), 3.56-3.38 (m, 2 H), 2.22 (s, 3 H); LC/MS (m/z) ES+=228 (M+1).