Hydrochloric Acid → 1-(5-Chloro-6-methylpyridin-2-yl)-5-methyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Steps

Water (4 ml) and concentrated hydrochloric acid (1 ml) were added to 1-(5-amino-6-methylpyridin-2-yl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester (260 mg) described in Reference Example 31(3), and then sodium nitrite (83 mg) was added therein at 0° C. After stirring for 0.5 hour, sodium nitrite (83 mg) was added again and stirred for an hour. Then copper (I) chloride (485 mg) was added and stirred in a water bath for 20 minutes. The reaction solution was added to a saturated aqueous solution of sodium bicarbonate and filtered through Celite. Water was added to the filtrate, extracted with ethyl acetate and the organic layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The resulting residue was reacted and treated in a similar manner as Reference Example 24(3) to give the titled compound (112 mg) as a brown solid.

Provenance & Evidence