Carbon Dioxide → 3-Bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

2-(3-Bromo-pyrazol-1-yl)-3-chloro-pyridine (9.2 g) was dissolved in dry THF (80 mL) and cooled to −78° C. A solution of LDA (21.3 mL, 2.0 M) was added over a period of 10 min and stirred for further 15 min at −78° C. The solution was poured on crushed dry ice in THF (50 mL) and stirred for additional 1 h. Water and Et2O were added and 2N NaOH-solution was added to adjust the pH to 10-12. The layers were separated and the aqueous layer was washed 2× with Et2O and acidified with 2N HCl (pH ˜3). The resulting suspension was 3× extracted with MTB-ether, the combined org. layers were washed with brine, dried over MgSO4 and concentrated to afford 7.96 g of the title compound of the formula

Provenance & Evidence