Synthesis, crystal structure and Hirshfeld surface analysis of Fmoc-β-amino butyric acid and Fmoc carbamate

In the context of the development of synthetic routes that facilitate the incorporation of β-amino acids into peptide synthesis, the synthesis, crystal structure and Hirshfeld surface analysis are reported of fluorenyl-meth-oxy-carbonyl (Fmoc) protected β-amino butyric acid, namely, 3-{[(9H-fluoren-9-ylmeth-oxy)carbon-yl]amino}-butanoic acid, C₁₉H₁₉NO₄. The importance of pH control in the reaction employing Fmoc-N₃ is demonstrated with another β-amino acid analogue from which Fmoc carbamate was identified as the major product.