Sodium Hydroxide → 2,2,2-Trichloroethyl 3-tert-butyl-1-(4-cyanophenyl)-1H-pyrazol-5-ylcarbamate

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Reaction Steps

To a suspension of Intermediate 71a (2.28 g, 9.49 mmol) in EtOAc (25 mL) and aqueous NaOH (1M, 23.7 mL, 23.7 mmol) was added 2,2,2-trichloroethyl chloroformate (1.57 mL, 11.4 mmol) dropwise over 2 min. A precipitate formed which redissolved after 15 min, then the orange solution was stirred at RT for 90 min. 2,2,2-Trichloroethyl chloroformate (0.391 mL, 2.85 mmol) was added and the orange mixture stirred at RT for 16 h. The layers were separated and the aqueous extracted with EtOAc (25 mL). The combined organics were washed with brine (25 mL), dried (Na2SO4), filtered and concentrated in vacuo to leave an orange-red oil. Recrystallisation from cyclohexane gave an off-white solid (3.12 g, 79%). LCMS (Method 3): Rt 4.46 min, m/z 415, 417 [MH+].

Provenance & Evidence