One-Step Synthesis of 3-(Fmoc-amino acid)-3,4-diaminobenzoic Acids

A one-step method for synthesizing 3-(Fmoc-amino acid)-3,4-diaminobenzoic acids was used to prepare preloaded diaminobenzoate resin. The coupling of free diaminobenzoic acid and Fmoc-amino acids gave pure products in 40-94% yield without any purification step in addition to precipitation except for histidine. For the proline residue, crude products were collected and used for solid-phase peptide synthesis to give a moderate yield of a pentapeptide. In addition, this method was used to prepare unusual amino acid derivatives, namely, (2-naphthyl) alanine and 6-aminohexanoic acid derivatives, in 50 and 65% yield, respectively.

Automated summary

A one-step synthesis method was used to prepare preloaded diaminobenzoate resin. The method enables the synthesis of pure products in high yield without the need for purification steps, except for histidine. It can also be used for solid-phase peptide synthesis and the preparation of unusual amino acid derivatives, with good yields.