4-Isoxazolecarboxylicacid,3-cyclopropyl-(9CI) synthesis

Yield:639523-17-4 94%

Reaction Conditions:

Stage #1: 3-cyclopropyl-isoxazole-4-carboxylic acid ethyl esterwith water;potassium hydroxide in ethanol at 0 - 20;
Stage #2: with hydrogenchloride in ethanol;water; pH=2;

Steps:

1

5.6 g (31 mmol) of 3-Cyclopropyl-isoxazole-4-carboxylic acid ethyl ester were slowly added to a solution of 6.1 g (93 mmol, 85% purity) of potassium hydroxide in ethanol/water (1 :3, 100 ml) at 0 ⁰C. The reaction mixture was stirred at room tem- perature for 16 h, diluted with water, acidified (pH = 2) with 20 % aqueous HCI and extracted with dichloromethane. The combined organic layers were dried over sodium sulfate, filtered and the solvent was removed to yield 4.7 g (94%, 95% purity) of the title compound which did not need further purification.

References:

WO2011/3793,2011,A1 Location in patent:Page/Page column 87