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

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence