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.

中文翻译：

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3-(Fmoc-氨基酸)-3,4-二氨基苯甲酸的一步合成

采用一步合成3-(Fmoc-氨基酸)-3,4-二氨基苯甲酸的方法制备预负载二氨基苯甲酸酯树脂。游离二氨基苯甲酸和 Fmoc-氨基酸的偶联得到纯产物，产率 40-94%，除了沉淀之外，除了组氨酸之外，无需任何纯化步骤。对于脯氨酸残基，收集粗产物并用于固相肽合成，得到中等产率的五肽。此外，该方法还用于制备不常见的氨基酸衍生物，即(2-萘基)丙氨酸和6-氨基己酸衍生物，收率分别为50%和65%。