Potassium Hydroxide → 4-ethoxy-1-(4-fluorophenyl)-1H-pyrazole-3-carboxylic acid

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Reaction Steps

D2 (38 mmol, 1.0 eq.) and aq. KOH-solution (3M, 190 mmol, 5.0 eq.) in EtOH (152 mL) were heated for 45 min at 50° C. The mixture was cooled to RT and diluted with DCM and water. The aq. phase was washed a second time with DCM. The aq. phase was acidified with aq. HCl-solution (1N) to pH=1 and extracted with EtOAc. The combined organic phase was washed with brine and dried over Na2SO4. Removal of the solvent yielded the product D3 as a brown solid (8.88 g, 93% over 2 steps). 1H NMR (400 MHz, d6-DMSO, 300K) δ 1.34 (t, J=7.0 Hz, 3H), 4.02 (q, J=7.0 Hz, 2H), 7.37 (dd, J=J=9.0 Hz, 2H), 7.87 (dd, J=9.0 Hz, J=4.6 Hz, 2H), 8.38 (s, 1H), 12.68 (br s, 1H). MS (ES) C12H11FN2O3 requires: 250. Found: 251 (M+H)+ and 273 (M+Na)+.

Provenance & Evidence