Piperazine → [1-(4-Chlorobenzyl)-2-oxo-2-piperazin-1-yl-ethyl]-carbamic acid tert-butyl ester

Participants

Reaction Steps

To a solution of Boc-D-Phe(4-Cl)—OH (3.65 g, 12.2 mmol), piperazine (10 g, 116 mmol) in DCM (200 mL) were added HOBT (3.3 g, 24 mmol) and EDCI (4.7 g, 25 mmol). The mixture was stirred at room temperature for 12 hours. The solution was washed with water, brine and dried over magnesium sulfate. After filtration, the organic solvent was evaporated and the residue was subject to silica gel chromatography to afford the product [1-(4-chlorobenzyl)-2-oxo-2-piperazin-1-yl-ethyl]-carbamic acid tert-butyl ester (0.58 g, 13%). 1H NMR (CDCl3, 400 Hz) δ 7.25 (d, J=8.4 Hz, 2H), 7.12 (d, J=8.0 Hz, 2H), 5.52 (d, J=8.4 Hz, 1H), 4.83-4.77 (m, 1H), 3.63-3.45 (m, 2H), 3.37-3.32 (m, 1H), 3.08-3.04 (m, 1H), 2.99-2.90 (m, 2H), 2.81-2.70 (m, 3H), 2.42-2.38 (m, 1H), 1.41 (s, 9H). MS (ESI+) [M+H]+ 369.

Provenance & Evidence