Hydrochloric Acid → (S)-tert-butyl 4-(3-(1-hydroxyethyl)benzyl)piperazine-1-carboxylate

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Reaction Steps

Under a positive pressure of N2 1-1.5M solution of (S)-Methyl oxazaborolidine (0.5 mL, 5.0 mmol) was diluted in 2 mL of toluene and treated with 3.6 mL of borane-N,N-diethylaniline. The tert-butyl 4-(3-acetylbenzoyl)piperazine-1-carboxylate from above in 3 mL of anhydrous toluene was added to the above solution over 1 hour and stirred for an additional hour. The mixture was stirred at 20° C. for another hour. To the mixture was added 6 mL MeOH, 12 mL 1N HCl and the resultant mixture stirred for 20 min. The mixture was diluted with 50 mL toluene and washed with saturated NaCl (50 mL). The organic extracts were dried over Na2SO4, filtered and concentrated at reduced pressure. The residue was heated at reflux in Et2NH for 1 hour. Purification by reverse-phase HPLC to afforded (S)-tert-butyl 4-(3-(1-hydroxyethyl)benzyl)piperazine-1-carboxylate as 1.08 g of white solid.

Provenance & Evidence