Trifluoroacetic anhydride → HCID 86728142, compound

Temperature

0 °C

To a solution of methyl 3-methylpyrazine-2-carboxylate (9.1 g, 59.8 mmol) in DCM (100 mL) at 0° C., was added urea hydrogen peroxide adduct, 97% (7.81 g, 83 mmol) and trifluoroacetic acid anhydride (10.8 ml, 78 mmol) dropwise. The resulting mixture was stirred at 0° C. for 1 h, and at room temperature for 18 h. The reaction was diluted with DCM and quenched with saturated Na2SO3 solution; the aqueous layer was back-extracted with DCM. The combined organic extracts were dried (MgSO4), filtered and concentrated in vacuo. The crude mixture was purified with ISCO (20% to 80% EtOAc/Hexanes) to afford a mixture of products: 2-(methoxycarbonyl)-3-methylpyrazine 1-oxide (5.2 g, 51.7% yield) and 3-(methoxycarbonyl)-2-methylpyrazine 1-oxide. The mixture was taken to next step without further purification.

1. waitat room temperature for 18 h
2. customquenched with saturated Na2SO3 solution
3. extractionthe aqueous layer was back-extracted with DCM
4. dry with materialThe combined organic extracts were dried (MgSO4)
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customThe crude mixture was purified with ISCO (20% to 80% EtOAc/Hexanes)
8. customto afford
9. additiona mixture of products

ORD record

ord-ac510f0b48b345f09c0b4d7c7e7391db

Source dataset

uspto-grants-2016_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09309263B2