2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 5-Bromo-3-methyl-1,2-benzoxazole

Participants

Reaction Steps

To a stirred solution of triphenylphosphine (6.8 g, 26.1 mmol) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) (3.9 g, 26.1 mmol) in CH2Cl2 (50 mL) was added (E)-1-(5-bromo-2-hydroxyphenyl)ethanone oxime (11) (5.0 g, 21.73 mmol) in small portions over a period of 15 min. The mixture was stirred for additional 10 min at room temperature and then the solvent was removed under reduced pressure. The residue was purified by flash column chromatography (silica gel, eluting with 5% ethyl acetate and hexanes) to give the title compound (12) (3.0 g, 65%) as a brown solid. 1H NMR (CDCl3, 400 MHz) δ 7.79 (s, 1H), 7.40 (dd, J=8.4, 1.6 Hz, 1H), 7.35 (d, J=8.4 Hz, 1H), 2.64 (s, 3H); MS (ESI, M+H+) C8H7BrNO, calcd. 212.0. found 212.0, 214.0.

Provenance & Evidence