Hydrochloric Acid → 6-Chloro-1,3-dihydropyrrolo[3,2-B]pyridin-2-one

In a dry flask fitted with a nitrogen inlet and mechanical stirrer was placed sodium hydride as a 60° suspension in oil (4.0 g, 0.10 mol). Most of the oil was removed by washing twice with hexanes. The remaining solid sodium hydride was then suspended in dry 1,2-dimethoxyethane (DME) (125 mL). To the resulting slurry was added dropwise, with stirring, a solution of diethyl malonate (15.7 mL, 0.10 mol) in DME (50 mL). The mixture was stirred at room temperature for 1 hour after which a solution of 2,5-dichloro-3-nitropyridine (10 g, 51.8 mmol) in DME (75 mL) was added. Stirring at room temperature was continued overnight and the reaction mixture was diluted with water. Following acidification to pH 2 with 1N HCl solution, the mixture was extracted with ether. The ether phase was washed with brine, dried over MgSO4 and concentrated in vacuo to leave a red oil. This was subjected to flash chromatography on silica gel using 9:1 hexane/ethyl acetate as eluant. All fractions containing the desired product were combined and concentrated to yield 2-bis(ethoxycarbonyl)methyl-5-chloro-3-nitropyridine as an oil (13.6 g, 82%).

1. customIn a dry flask fitted with a nitrogen inlet and mechanical stirrer
2. customas a 60°
3. customMost of the oil was removed
4. washby washing twice with hexanes
5. additionTo the resulting slurry was added dropwise
6. additionwas added
7. stirringStirring at room temperature
8. extractionthe mixture was extracted with ether
9. washThe ether phase was washed with brine
10. dry with materialdried over MgSO4
11. concentrationconcentrated in vacuo
12. customto leave a red oil

ORD record

ord-e7bf9972fcc64c728b25d5c2beebaddc

Source dataset

uspto-grants-1998_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05811432