1-(2-Methoxyethyl)-1H-Pyrazole-3-carboxylic acid synthesis

Yield:-

Reaction Conditions:

Stage #1:Ethyl 1-(2-methoxyethyl)-1H-pyrazole-3-carboxylate with sodium hydroxide;water in ethanol at 20; for 3 h;
Stage #2: with hydrogenchloride in water

Steps:

30 1-(2-Methoxyethyl)-1H-pyrazole-3-carboxylic acid
Preparation 30 1-(2-Methoxyethyl)-1H-pyrazole-3-carboxylic acid Ethyl 1-(2-methoxyethyl)-1H-pyrazole-3-carboxylate (Preparation 28, 360 mg, 1.8 mmol) was dissolved in ethanol (6 ml), a solution of sodium hydroxide (90 mg, 2.3 mmol) in water (3 ml) was added and the solution was stirred at room temperature for 3 hours. The ethanol was removed in vacuo and the residue was acidified with 2M HCl (approximately 1.5 ml), the aqueous solution was evaporated to dryness in vacuo and the residue was extracted with a mixture of dichloromethane (15 ml) and 3 drops of methanol. The mixture was filtered to remove the inorganics and the solvent removed in vacuo to give 310 mg of a yellow oil which crystallized on standing. ¹H-NMR (CDCl₃): 3.33 (s, 3H), 3.78 (t, 2H), 4.40 (t, 2H), 6.86 (d, 1H), 7.54 (d, 1H) MS m/z 171 [MH]+

References:

Pfizer Limited US2007/105872, 2007, A1 Location in patent:Page/Page column 33