6-Bromo-2H-pyrido[3,2-B][1,4]oxazin-3(4H)-one → 3-Oxo-3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazine-6-carbaldehyde

HRID 885677Notes

Reaction equation

HRID 885677 reaction equation
Br[C:2]1[CH:3]=[CH:4][C:5]2[O:6][CH2:7][C:8](=[O:12])[NH:9][C:10]=2[N:11]=1.[CH2:13]([O:15]C(=O)COC1C([N+]([O-])=O)=NC(Br)=CC=1)C>C(O)(=O)C.CCOC(C)=O.[Fe]>[O:12]=[C:8]1[CH2:7][O:6][C:5]2[CH:4]=[CH:3][C:2]([CH:13]=[O:15])=[N:11][C:10]=2[NH:9]1

Participants

6

Reactant 2

HCID 218737726-Bromo-2H-pyrido[3,2-B][1,4]oxazin-3(4H)-oneHCID 59560649Ethyl (6-bromo-2-nitropyridin-3-yloxy)acetate

Product 1

HCID 218737373-Oxo-3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazine-6-carbaldehydeYield 57%

Reagents, catalysts & solvents 3

HCID 23925IronCatalystHCID 176Acetic AcidSolventHCID 8857Ethyl AcetateSolvent

Conditions

Temperature
90 °C

Procedure

6-Bromo-4H-pyrido[3,2-b][1,4]oxazin-3-one. To a solution of (6-bromo-2-nitro-pyridin-3-yloxy)-acetic acid ethyl ester (3.14 g, 10.3 mmol) in glacial acetic acid (12.4 mL) was added iron powder (1.67 g, 29.9 mmol). The suspension was heated to 90° C. and stirred for 6 h, after which it was cooled to RT and diluted with EtOAc (50 mL). The mixture was filtered through a pad of SiO2 and the filtrate was concentrated. Recrystallization from CH3OH provided 1.32 g (57%) of the title compound as a solid. MS (ESI): exact mass calculated for C7H5BrN2O2, 227.95; m/z found, 228.2 [M+H]+. 1H NMR (400 MHz, CDCl3): 7.98 (d, J=5.3, 1H), 7.16-7.09 (m, 1H), 6.98 (dd, J=8.0, 4.9, 1H), 4.68 (d, J=1.4, 2H).

Workup

  1. temperatureafter which it was cooled to RT
  2. filtrationThe mixture was filtered through a pad of SiO2
  3. concentrationthe filtrate was concentrated
  4. customRecrystallization from CH3OH

Sources & evidence

ORD record
ord-5102b2ae71024ff9bf6ffd403a596aee
Source dataset
uspto-grants-2012_08
Patent number
US08242275B2

Reaction notes

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