Acetic Anhydride → 6-Bromo-4-methoxypyrazolo[1,5-a]pyridine-3-carbonitrile

Temperature

50 °C

The oxime isomer mixture of 6-bromo-4-methoxypyrazolo[1,5-a]pyridine-3-carbaldehyde oxime (85.0 mg, 0.315 mmol) was suspended in acetic anhydride (3.0 ml, 31.8 mmol) and heated to 50° C. for 3 h to give a pale blue solution. The solution was then heated to 75° C. for 2 h to give a dark blue solution. The solution was then heated to 100° C. overnight to give a dark purple mixture. The reaction mixture was concentrated and the residue was diluted in ethyl acetate, washed with saturated aqueous sodium hydrogen carbonate and brine then dried over sodium sulfate, filtered and concentrated. The residue was purified by column chromatography on silica gel (ethyl acetate/isohexane gradient) to give 6-bromo-4-methoxypyrazolo[1,5-a]pyridine-3-carbonitrile.

1. customto give a pale blue solution
2. temperatureThe solution was then heated to 75° C. for 2 h
3. customto give a dark blue solution
4. temperatureThe solution was then heated to 100° C. overnight
5. customto give a dark purple mixture
6. concentrationThe reaction mixture was concentrated
7. additionthe residue was diluted in ethyl acetate
8. washwashed with saturated aqueous sodium hydrogen carbonate and brine
9. dry with materialthen dried over sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated
12. customThe residue was purified by column chromatography on silica gel (ethyl acetate/isohexane gradient)

ORD record

ord-76fa1095a8af4e38904b1c110ac573ee

Source dataset

uspto-grants-2013_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08455477B2