2-[4-(tert-Butoxycarbonyl)piperazin-1-yl]benzoic acid → tert-Butyl 4-[2-(hydroxymethyl)phenyl]piperazine-1-carboxylate

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Reaction Steps

4-(2-Carboxyphenyl)piperazine-1-carboxylic acid t-butyl ester (3.5 g, 11.3 mmol, 1.0 eq.) and THF (91.3 mL) were combined at room temperature under nitrogen. Borane-dimethyl sulfide complex (2.00 mL, 22.5 mmol, 2.0 eq.) was added dropwise and the mixture was stirred for 5 minutes, then heated at the reflux temperature for 1.5 hours. The mixture was cooled to room temperature, and the reaction was quenched slowly with MeOH (20 ml), then concentrated by rotary evaporation. The material was azeotroped with MeOH (2×20 ml). The crude product was dissolved in EtOAc (50 ml), and washed with cold 1M HCl (2×25 ml), then NaHCO3 (2×25 ml). The organic layer was dried over anhydrous Na2SO4, filtered, and concentrated in vacuo to yield the title compound (1.3 g) as a clear oil that solidified upon sitting.

Provenance & Evidence