Sodium Hydroxide → [5-tert-Butyl-2-(4-hydroxymethyl-phenyl)-2H-pyrazol-3-yl]-carbamic acid 2,2,2-trichloro-ethyl ester

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Reaction Steps

To a suspension of [4-(5-amino-3-tert-butyl-pyrazol-1-yl)-phenyl]-methanol (WO 2011/070368, which is incorporated herein by reference in its entirety; 3.05 g, 12.4 mmol) in aq. NaOH solution (1 M, 31 mL, 31 mmol) and EtOAc (30 mL) at RT was added 2,2,2-trichloroethyl chloroformate (1.88 mL, 13.7 mmol) over 3 min (CARE: exotherm to 35° C.) and the mixture stirred at RT for 1 h. The aqueous layer was extracted with EtOAc (20 mL), then the combined organics washed with brine (25 mL), dried (Na2SO4), filtered and concentrated in vacuo to leave a pale orange solid. Recrystallisation from hot cyclohexane-EtOAc (3:1, 30 mL) and drying in vacuo gave the title compound as a flocculent off-white solid (3.87 g, 74%). LCMS (Method 3): Rt 4.00 min, m/z 420, 422 [MH+].

Provenance & Evidence