Acetohydroxamic Acid → 5-Bromo-1,2-benzoxazol-3-amine

The title compound was prepared by a modification of the literature procedure as described in Palermo, M. G., Tetrahedron Lett., 37:2885 (1996). A single neck 50 mL flask equipped with a magnetic stirred was charged with N-hydroxyacetamide (2.63 g, 35.0 mmol) and DMF (100 mL). Then, KOtBu (3.93 g, 35.0 mmol) was added in one portion. The temperature rose to 30° C. The mixture was stirred for 1 h and, 5-bromo-2-fluorobenzonitrile (7 g, 35.0 mmol) was added. The reaction mixture was stirred for overnight. A further portion of KOtBu (1.96 g, 17.5 mmo) was added and the solution was again stirred overnight. The mixture was poured into brine and CH2Cl2 and the layers were separated. The organic phase was dried (Na2SO4) and concentrated in vacuo. The residue was purified by flash column chromatography (BIOTAGE®, eluting with a gradient of 0 to 40% EtOAc in hexanes) to afford the title compound (4.59 g, 62%) as a colorless solid. 1H NMR (500 MHz, DMSO-d6) δ 8.09 (d, J=1.8 HZ, 1H), 7.65 (dd, J=2.1, 8.9 Hz, 1H), 7.45 (d, J=8.9 Hz, 1H), 6.49 (s, 2H). LCMS: Anal. Calcd. for C7H5BrN2O: 211, 213; found: 212, 214 (M+H)+.

1. customThe title compound was prepared by a modification of the literature procedure
2. customA single neck 50 mL flask equipped with
3. customrose to 30° C
4. stirringThe mixture was stirred for 1 h
5. stirringThe reaction mixture was stirred for overnight
6. customthe layers were separated
7. dry with materialThe organic phase was dried (Na2SO4)
8. concentrationconcentrated in vacuo
9. customThe residue was purified by flash column chromatography (BIOTAGE®
10. washeluting with a gradient of 0 to 40% EtOAc in hexanes)

ORD-Eintrag

ord-0c9a05967f564fe3a906c08c43b3df89

Quelldatensatz

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08211928B2