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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence