Diisopropylethylamine → (S)-Methyl 6-amino-2-((tert-butoxycarbonyl)amino)hexanoate

Participants

Reaction Steps

A 1M stock solution of (S)-methyl 6-amino-2-(tert-butoxycarbonylamino)hexanoate in 20 mL DMF was prepared, and used. A 2 mL aliquot of the (S)-methyl 6-amino-2-(tert-butoxycarbonylamino)hexanoate stock solution, 3-oxocyclobutanecarboxylic acid (2) (Parkway *BX-102, 283 mg), HATU (800 mg), DIEA (1.0 mL) and 8 mL DMF were combined in a 40 mL glass vial, and stirred at ambient temperature overnight. The LC-MS analysis revealed a complete reaction. The reaction mixture was diluted with EtOAc, washed successively with water, sat aq. NaCl, dried over MgSO4, filtered and concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography (hexanes/EtOAc), affording (S)-methyl 2-(tert-butoxycarbonylamino)-6-(3-oxocyclobutanecarboxamido)hexanoate (TU3000-140) as a clear viscous oil. MS (ESI+): calcd. 379.18. found 379.20 (MNa+), calcd. 257.15. found 257.20((M-Boc)H+). H-NMR (400 MHz, DMSO-d6):1.245 (4H, m), 1.371 (9H, s), 1.579 (2H, m), 3.065 (3H, m), 3.135 (4H, m), 3.608 (3H, s), 3.895 (1H, m), 7.209 (1 h, d, J=8.0 Hz), 8.123 (1H, t, J=5.4 Hz). C-NMR (100 MHz, DMSO-d6): 22.850, 27.185, 28.111, 28.551, 30.209, 38.276, 50.859, 51.639, 53.412, 53.529, 78.137, 155.507, 172.992, 173.167, 205.576.

Provenance & Evidence