Ethyl Acetate → Methyl 6-bromo-2,2-dimethyl-3-oxo-1,2,3,4-tetrahydroquinoxaline-5-carboxylate

Methyl 6-bromo-3-[(2-ethoxycarbonyl)propan-2-yl]amino-2-nitrobenzoate (Reference Compound No. 1-(5), 105 mg, 0.26 mmol) was dissolved in anhydrous ethanol (4.5 mL), tin (II) chloride (247 mg, 1.30 mmol) was added thereto, and then the reaction mixture was refluxed for 5 hours. After the reaction mixture was cooled down, ethyl acetate (25 mL) was added thereto, the mixture was neutralized with aqueous sodium hydrogen carbonate solution, and then filtered on celite. After the filtrate was partitioned, the water layer was extracted with ethyl acetate (10 mL, twice), the combined organic layer was washed with water (50 mL, twice) and saturated brine (50 mL) successively, dried over anhydrous magnesium sulfate, and then the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane-ethyl acetate) to give the titled reference compound (56.3 mg) as a pale yellow solid. (Yield 70%)

1. temperaturethe reaction mixture was refluxed for 5 hours
2. temperatureAfter the reaction mixture was cooled down
3. filtrationfiltered on celite
4. customAfter the filtrate was partitioned
5. extractionthe water layer was extracted with ethyl acetate (10 mL
6. washtwice), the combined organic layer was washed with water (50 mL
7. dry with materialtwice) and saturated brine (50 mL) successively, dried over anhydrous magnesium sulfate
8. customthe solvent was removed under reduced pressure
9. customThe obtained residue was purified by silica gel column chromatography (hexane-ethyl acetate)

ORD record

ord-189615f98ef64a7da6ba18be4359680f

Source dataset

uspto-grants-2012_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08193187B2