Sodium Hydroxide → 5-phenoxymethyl-1H-pyrazole-3-carboxylic acid

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Reaction Steps

Freshly prepared aq. NaOH (10 M in H2O, 10.49 mmol) was added to a stirring, room temperature solution of 41 (0.5164 g, 2.10 mmol) in MeOH (5.2 mL, 0.4 M) under N2. The reaction was then heated to reflux until the reaction was judged complete by HPLC (20 min): The reaction was concentrated and then dissolved in 4.2 mL H2O. 10% aq. HCl was added dropwise until the pH=2. The white solid that precipitated from the reaction was filtered off and washed with cold H2O. The solid was dried under vacuum overnight to obtain 0.4044 g (88.4%) of 42 as a white solid. Note: An undesired impurity that does not crash out of solution upon HCl addition has a retention time of 9.127 min by 1H (CDCl3, 400 MHz): δ 7.26 (2H, t, J=8.0 Hz), 6.99 (2H, d, J=8.3 Hz), 6.94 (1H, t, J=7.3 Hz), 6.85 (1H, s), 5.10 (2H, s) ppm. 13C (CDCl3, 100 MHz): δ 163.68, 159.73, 146.60, 141.13, 130.51, 122.27, 115.83, 108.88, 63.06 ppm. DEPT (CDCl3, 100 MHz): CH2 carbons: 63.06; CH carbons: 130.51, 122.27, 115.83, 108.88 ppm. HPLC: 8.272 min.

Provenance & Evidence