反応 #41102

反応方程式

5-Chloro-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

Sodium hydride

pyrazole

Water

→

2′-methyl-2′H-[1,3′]bipyrazolyl-4′-carboxylic acid ethyl ester

収率 9.1%

溶媒

DMF

ethyl acetate

反応条件

後処理

1. 1
   温度the mixture was heated to 100° C. overnight
2. 2
   温度cooled
3. 3
   その他the organic layer was separated
4. 4
   抽出the aqueous phase was extracted three times with EtOAc
5. 5
   濃縮The combined organic phases were concentrated in vacuo
6. 6
   その他the residue was purified by flash silica chromatography
7. 7
   洗浄eluting with a gradient of 0-20% ethyl acetate/hexanes

実験手順

Sodium hydride (60% in oil; 767 mg, 19 mmol) was added to a solution of pyrazole (1.36 g, 20 mmol) in dry DMF (40 mL) under nitrogen at 0° C. in an ice-water bath and the mixture was heated to 40° C. for 1 h. 5-Chloro-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (1.89 g, 10 mmol) was added and the mixture was heated to 100° C. overnight and then cooled. Water and ethyl acetate were added, the organic layer was separated, and the aqueous phase was extracted three times with EtOAc. The combined organic phases were concentrated in vacuo and the residue was purified by flash silica chromatography eluting with a gradient of 0-20% ethyl acetate/hexanes, then 20% ethyl acetate/hexanes to give 2′-methyl-2′H-[1,3′]bipyrazolyl-4′-carboxylic acid ethyl ester (0.2 g, 9%).

出典