2(3H)-Benzoxazolone → 3-(2-Chloroethyl)-1,3-benzoxazol-2(3H)-one

Sodium hydride (3.9 g, mmol, 50% mineral oil dispersion) was washed with hexane to remove mineral oil (3×10 ml) under a stream of nitrogen. A solution of 1,3-benzoxazolin-2-one (Aldrich, 10 g, 74 mmol) in dimethylformamide (DMF) (70 ml) was then added dropwise with stirring to the hydride until hydrogen evolution ceased. The reaction flask was immersed in an ice bath and 2-bromochloroethane (12.3 ml, 148 mmol) in dimethylformamide (30 ml) was added dropwise. The reaction mixture was stirred at room temperature for 30 minutes, then heated to reflux for 3 days. At the end of this time thin layer chromatography analysis showed consumption of starting material. The reaction mixture was then cooled and the solvent evaporated under vacuum. The residue was worked-up as described above and purified by column chromatography (400 g fine silica, chloroform-methanol-ammonium hydroxide, 80:1:0.1) to yield 11.7 g (80%) of pure 2-(2-oxo-1,3-benzoxazolin-3-yl)ethyl chloride (mp. 77°-79° C. as a pale orange solid.

1. washSodium hydride (3.9 g, mmol, 50% mineral oil dispersion) was washed with hexane
2. customto remove mineral oil (3×10 ml) under a stream of nitrogen
3. customThe reaction flask was immersed in an ice bath
4. temperatureheated
5. temperatureto reflux for 3 days
6. customconsumption of starting material
7. temperatureThe reaction mixture was then cooled
8. customthe solvent evaporated under vacuum
9. custompurified by column chromatography (400 g fine silica, chloroform-methanol-ammonium hydroxide, 80:1:0.1)

ORD record

ord-0034aa27a4334a3e894997873842c41a

Source dataset

uspto-grants-1993_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

USRE034201