2-Ethylbutyraldehyde → 1-[1-(Benzyloxy)-1H-pyrazol-5-yl]-2-ethylbutan-1-ol

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Reaction Conditions

Reaction Steps

To 1-benzyloxy-1H-pyrazole (prepared as described in JOC 60:4996 1995) dissolved in THF (20 mL) and cooled to −78° C. under a nitrogen atmosphere was added a solution of n-butyllithium (1.6 M in hexane, 2.0 mL, 3.2 mmol) via syringe over 10 min. After stirring at the above temperature for 1.25 h, 2-ethyl-butyraldehyde (0.42 mL, 3.4 mmol) was added dropwise. The mixture was then stirred at −78° C. for 1.5 h and quenched by dropwise addition of saturated aqueous ammonium chloride solution (3 mL). The mixture was warmed to ambient temperature and diluted with EtOAc, washed with saturated aqueous NaCl and the organic phase was dried over MgSO4. Filtration and evaporation of the organic extract produced an oil that was purified on a Biotage column (hexane/EtOAc, 6:1) to give the product as a clear colorless oil (0.565 g, 72%). Mass Spectrum (+ESI): 275 (M+H)+.

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