Synthesis
The general procedure for the synthesis of Fmoc-L-2,4-diaminobutyric acid (Fmoc-Dab-OH) from (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-amino-5-oxopentanoic acid (Fmoc-Gln-OH) was as follows:
A. 100 g (271.5 mmol) of Fmoc-Gln-OH was suspended in 2 L of a solvent mixture consisting of ethyl acetate, acetonitrile and water in the ratio of 2:1:1 by volume. 105.1 g (325.9 mmol) of diisopropylethylamine (DIPA) was slowly added at 20-30 °C and the reaction lasted for 72 hours. Upon completion of the reaction, 80 g of Fmoc-Dab-OH was obtained after post-processing in 86.5% yield. The product was analyzed by high performance liquid chromatography (HPLC) showing a purity of 99.6%, and its structural correctness was confirmed by infrared spectroscopy (IR) and nuclear magnetic resonance (NMR), and the relevant spectra are shown in Figures 1 and 2.
References
[1] Bulletin of the Chemical Society of Japan, 2004, vol. 77, # 10, p. 1915 - 1924
[2] Patent: CN105348147, 2016, A. Location in patent: Paragraph 0014
[3] Synlett, 2011, # 13, p. 1917 - 1919
[4] Journal of Peptide Science, 2017, vol. 23, # 3, p. 202 - 214
[5] European Journal of Medicinal Chemistry, 1995, vol. 30, # 2, p. 115 - 122
