n-Boc-4-(2-cyclopropyl-4-hydroxymethyl-2h-pyrazol-3-yl)-piperidine → N-Boc-4-(2-cyclopropyl-4-formyl-2H-pyrazol-3-yl)-piperidine

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Reaction Steps

The above acid (300 mg, 0.894 mmol) was dissolved in 5 mL of THF. To this solution was added 3.58 mL (3.58 mmol) of 1M borane in THF. After stirring for 5 h, the mixture was poured into 15 mL of 5% HCl. The solution was extracted with 200 mL of EtOAc, and the extract was washed with saturated NaHCO3 and brine, dried over MgSO4, filtered, concentrated, and chromatographed (10-100 EtOAc in hexanes) to give 120 mg of N-Boc-4-(2-cyclopropyl-4-hydroxymethyl-2H-pyrazol-3-yl)-piperidine. This alcohol (100 mg, 0.31 mmol) was stirred overnight in 10 mL of THF with 270 mg (3.1 mmol) of activated MnO2. The mixture was filtered and concentrated to provide 70 mg of N-Boc-4-(2-cyclopropyl-4-formyl-2H-pyrazol-3-yl)-piperidine.

Provenance & Evidence