As a commercially available and orthogonally protected amino acid building block, Fmoc-Dab(Mtt)-OH showed abnormally poor coupling efficiency during solid-phase peptide synthesis (SPPS). Herein, we reveal that Fmoc-Dab(Mtt)-OH undergoes rapid lactamization under a series of conditions with various coupling reagents. Although the complete incorporation of Fmoc-Dab(Mtt)-OH can be achieved using a multi-time and preincubation-free protocol with the coupling reagent DEPBT, alternative orthogonally protected building blocks are suggested to be used for avoiding such a costly and tedious procedure.

中文翻译：

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在固相肽合成过程中掺入 Fmoc-Dab(Mtt)-OH：注意事项

Fmoc-Dab(Mtt)-OH 作为一种市售且正交保护的氨基酸结构单元，在固相肽合成 (SPPS) 过程中显示出异常差的偶联效率。在这里，我们揭示了 Fmoc-Dab(Mtt)-OH 在一系列条件下与各种偶联剂发生快速内酰胺化。尽管使用偶联试剂 DEPBT 的多次且无需预孵育的方案可以实现 Fmoc-Dab(Mtt)-OH 的完全结合，但建议使用替代的正交保护构建块来避免这种昂贵且繁琐的程序.