4-Chloro-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid → 4-Chloro-1-ethyl-5-(5-isopropyl-1,3,4-oxadiazol-2-yl)-1H-pyrazolo[3,4-b]pyridine
反応式
[Cl:1][C:2]1[C:7]([C:8]([OH:10])=O)=[CH:6][N:5]=[C:4]2[N:11]([CH2:14][CH3:15])[N:12]=[CH:13][C:3]=12>S(Cl)(Cl)=O>[Cl:1][C:2]1[C:7]([C:8]2[O:10][C:4]([CH:3]([CH3:13])[CH3:2])=[N:11][N:12]=2)=[CH:6][N:5]=[C:4]2[N:11]([CH2:14][CH3:15])[N:12]=[CH:13][C:3]=12参加物
3
反応条件
- 温度
- 95 °C
実験手順
Intermediate 11 (0.05 g) was dissolved in thionyl chloride (1 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 (0.5 ml). This solution was added to a solution of isobutyric acid hydrazide (0.025 g) and diisopropylethylamine (0.058 ml) in anhydrous acetonitrile (1 ml), and the mixture stirred for a further 1.5 h. The mixture was concentrated in vacuo and the residue treated directly with phosphorus oxychloride (2 ml). The resultant solution was stirred and heated at reflux (120° C.) for 2 h, then allowed to cool and concentrated in vacuo. The residue was applied to an SPE cartridge (silica, 5 g) which was eluted sequentially with a gradient of EtOAc:cyclohexanI (i) 1:16, (ii) 1:8, (iii) 1:4, (iv) 1:2, (v) 1:1 and (vi) 1:0. Fractions containing desired material were combined and concentrated in vacuo to afford Intermediate 13 (0.049 g). LCMS showed MH+=292; TRET=2.96 min.