Nitrogen → Tert-butyl 4-(3-(aminomethyl)-4-chlorobenzyl)piperazine-1-carboxylate

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Reaction Steps

To a 250 mL round-bottom flask fitted with a reflux condenser, rubber septum and stir bar under a positive pressure of N2 was added 10.3 mL of 1M BH3.THF complex in THF. This mixture was cooled in an ice bath. The tert-butyl 4-(4-chloro-3-cyanobenzoyl)piperazine-1-carboxylate (1.44 g, 4.12 mmol) was dissolved in 20 mL of THF and added dropwise to the reaction mixture via syringe. The ice bath was removed, replaced with a heating mantle and the reaction mixture was heated at reflux for 20 h. The reaction was cooled to RT and to the mixture was added 48 mL of 20% HOAc in water (v/v) and the mixture was stirred between pH 3-4 for 20 h. The mixture was concentrated to half its original volume with a rotary evaporator and then diluted with 20 mL of 10% citric acid. This mixture was washed once with 25 mL of EtOAc and the aqueous layer was brought to pH=11 by the addition of 52 mL of 3N NaOH. The resultant mixture was extracted with EtOAc (3×40 mL). The combined extracts were washed with 40 mL of saturated NaCl solution. The organic layer was dried over Na2SO4, filtered and concentrated to give 1.00 g of tert-butyl 4-(3-(aminomethyl)-4-chlorobenzyl)piperazine-1-carboxylate as a pale yellow oil.

Provenance & Evidence