Hydrochloric Acid → 2-Fluoro-4-(1H-pyrazol-1-yl)benzaldehyde

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Reaction Steps

Diisobutylaluminum hydride (1.0 M in toluene, 11.00 mL, 11.00 mol) was added dropwise over 10 min to a vigorously stirred suspension of the compound from step A (1.88 g, 10.04 mmol) in toluene (100 mL) at −78° C. After 1 h at −78° C., MeOH (1 mL) was added, the mixture was stirred for 5 min, and then poured into a stirred, cold (0° C.) mixture of 1.2 N HCl (100 mL) and ethyl acetate (100 mL). After stirring for 30 min at RT, the layers were separated and the aqueous layer was extracted with additional ethyl acetate (100 mL). The combined organic layers were washed with sat. aq. NaHCO3 (100 mL) and brine (100 mL), dried (MgSO4), and concentrated. Recrystallization from IPA followed by chromatography (SiO2, dichloromethane) provided 1.25 g (65%) of the title compound as a colorless solid. MS 191 (M+H)+.

Provenance & Evidence