Potassium Carbonate → Tert-butyl 4-(4-formylphenyl)piperazine-1-carboxylate

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Reaction Steps

1-(t-Butoxycarbonyl)piperazine (1.86 g, 10 mmol), p-fluorobenzaldehyde 27 (1.24 g, 10 mmol), and K2CO3 (1.74 g, 11 mmol) in dry pyridine (10 mL) are stirred at reflux under a nitrogen atmosphere for 24 h. Most of the solvent is removed under vacuum and the residue is partitioned between EtOAc (150 mL) and water (100 mL). The aqueous layer is washed with EtOAc (2×50 mL) and the combined organic layers are sequentially washed with 3% aq. citric acid (2×100 mL), water (100 mL), brine (100 mL), and dried (MgSO4). The solvent is removed under vacuum and the residue washed with hexanes and dried under vacuum. The product can be used as such, or further purified by silica gel column chromatography (dichloromethane-MeOH gradient).

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