Dimethylformamide → 6,7-Dichloro-2,3-dimethoxy-5-(N-methylcarbamoyl)quinoxaline

To a solution of 6,7-dichloro-2,3-dimethoxyquinoxaline-5-carboxylic acid (Preparation 6, 0.890 g, 2.93 mmol) in dichloromethane (25 mL) at room temperature under nitrogen was added dry N,N-dimethylformamide (50 μL, 47.2 mg, 0.64 mmol) followed by oxalyl chloride (0.338 mL, 3.8 mmol). After 0.5 hours, the mixture was concentrated under reduced pressure. Dichloromethane (10 mL) was added to the residue at room temperature under nitrogen, followed by methylamine (33% w/w solution in ethanol, 10 mL, 80.3 mol). After 10 minutes, the mixture was evaporated under reduced pressure and the residue was partitioned between dichloromethane (20 mL) and 1M aqueous hydrochloric acid solution. The organic extract was dried (MgSO4) and evaporated under reduced pressure. The residue was purified by flash chromatography on silica gel, by gradient elution using dichloromethane:methanol (100:0 changing to 99:1, by volume) as the eluent to give a solid which was recrystallised from toluene to afford the title compound (0.570 g, 61%) as a white solid.

1. concentrationthe mixture was concentrated under reduced pressure
2. additionDichloromethane (10 mL) was added to the residue at room temperature under nitrogen
3. waitAfter 10 minutes
4. customthe mixture was evaporated under reduced pressure
5. customthe residue was partitioned between dichloromethane (20 mL) and 1M aqueous hydrochloric acid solution
6. extractionThe organic extract
7. dry with materialwas dried (MgSO4)
8. customevaporated under reduced pressure
9. customThe residue was purified by flash chromatography on silica gel, by gradient elution
10. customto give a solid which
11. customwas recrystallised from toluene

ORD record

ord-27a9b4865a0e4268bda7d51cbe6b4d9b

Source dataset

uspto-grants-2002_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06376490B1