Dicyclohexylcarbodiimide → Pentafluorophenyl N-tert-butoxycarbonyl-6-aminohexanoate

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Reaction Steps

To a solution of N-Boc-6-aminohexanoic acid (4.78 g, 20.8 mmol) and pentafluorophenol (3.68 g, 20 mmol) in 50 mL of EtOAc was added DCC (4.12 g, 20 mmol). This was allowed to stir for 16 h, and was then filtered and the filtrate evaporated in vacuo to a syrup. On standing, this crystallized to give 7.46 g (94%) of the ester. Rerystallization from isopropanol/1% acetic acid gave 6.26 g of white needles, mp 81°-83° C. 1H NMR (CDCl3) δ 1.4-1.6 (m, 15H, Boc CH3 and internal CH2), 1.8 (m, 2H, C2CH2CO2), 2.67 (5, J=7.3 Hz, 2H, CH2CO2), 3.1 (m, 2H, NHCH2), 4.5 (b, 1H, NH). 13C NMR (CDCl3) δ 24.38 (C4), 26.00 (C3), 28.39 (Boc CH3), 29.70 (C5), 33.20 (C2), 40.28 (C6), 79 (Boc C), 156 (Boc C=0), 169 (C1). Anal. Calcd for C17H20NO4F5 : C, 51.4; H, 5.1; N, 3.5. Found: C, 51.5; H, 5.0; N, 3.4.

Provenance & Evidence