1,1'-Carbonyldiimidazole → 4-(11-tert-Butoxycarbonylaminoundecanoyl)piperazine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

1,1′-Carbonyldiimidazole (118 mg, 0.73 mmol) was added to a solution of acid 3 (200 mg, 0.66 mmol) in tetrahydrofuran (5 mL) and the mixture stirred for 4 hours. A solution of N-tert-butoxycarbonylpiperazine (148 mg, 0.79 mmol) in tetrahydrofuran (2 mL) was added and the reaction stirred for an additional 14 hours at room temperature. The solvent was then removed under vacuum and the residual oil purified by column chromatography (silica gel, gradient 99:1 to 95:5 dichloromethane/methanol, v/v) to afford 7 (204 mg, 66%) as a white solid: 1H NMR (500 MHz, CDCl3) δ 1.27 (m, 12H), 1.41-1.51 (m, 21H), 1.56-1.66 (m, 5H), 2.32 (t, 2H, J=7.5 Hz), 3.08-3.11 (m, 2H), 3.38-3.41 (m, 2H), 3.56-3.59 (m, 2H), 4.51 (br, 1H); m/z (ESI) 470 [C25H47N3O5+H]+.

Provenance & Evidence