4-Chloro-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid → 4-Chloro-1-ethyl-5-(5-methyl-1,3,4-oxadiazol-2-yl)-1H-pyrazolo[3,4-b]pyridine

Temperature

95 °C

Intermediate 11 (0.4 g) was dissolved in thionyl chloride (3 ml) and the mixture was heated at reflux (95° C.) with stirring for 1 h. After cooling to room temperature, excess thionyl chloride was removed by evaporation under reduced pressure and the resultant solid dissolved in anhydrous acetonitrile (2 ml). This solution was added to a solution of acetic hydrazide (0.145 g) and diisopropylethylamine (0.465 ml) in anhydrous acetonitrile (2 ml), and the mixture stirred for a further 2 h. The mixture was concentrated in vacuo and the residue treated directly with phosphorus oxychloride (4 ml). The resultant solution was stirred and heated at reflux (120° C.) for 0.5 h, then allowed to cool and purified by Biotage (silica, 40 g), eluting with cyclohexane:EtOAc (1:1) to afford Intermediate 12 (0.32 g). LCMS showed MH+=264; TRET=2.55 min.

1. temperaturethe mixture was heated
2. temperatureAfter cooling to room temperature
3. customexcess thionyl chloride was removed by evaporation under reduced pressure
4. dissolutionthe resultant solid dissolved in anhydrous acetonitrile (2 ml)
5. additionThis solution was added to a solution of acetic hydrazide (0.145 g) and diisopropylethylamine (0.465 ml) in anhydrous acetonitrile (2 ml)
6. stirringthe mixture stirred for a further 2 h
7. concentrationThe mixture was concentrated in vacuo
8. additionthe residue treated directly with phosphorus oxychloride (4 ml)
9. stirringThe resultant solution was stirred
10. temperatureheated
11. temperatureat reflux (120° C.) for 0.5 h
12. temperatureto cool
13. custompurified by Biotage (silica, 40 g)
14. washeluting with cyclohexane:EtOAc (1:1)

ORD record

ord-679fc82ada1443a6b818ca13c681a715

Source dataset

uspto-grants-2009_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07528148B2