The anti-inflammatory drug, PMX205, is an antagonist of the C5a complement receptor and has been shown to be effective in rodent models of amyotrophic lateral sclerosis and Alzheimer’s disease. This cyclic hexapeptide (c[Arg-Trp-D-Cha-Pro-Orn]-Hca) has been reported to produce relatively low yields for both the linear peptide assembly and the cyclization reaction in solution and solid phase syntheses. During attempts to reproduce the solid phase methodology, a catastrophic loss of substitution was encountered which could be avoided or reduced by the use of 2-chlorotrityl resin. Likewise, the cyclization reaction could be significantly improved by the use of FDPP (pentafluorophenyl diphenylphosphinate) at high dilution (up to 80% purified yield). Both improvements are accomplished with commercially available products.

中文翻译：

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改进环六肽补体 C5a 拮抗剂 PMX205 的 Fmoc 固相合成。

抗炎药 PMX205 是 C5a 补体受体的拮抗剂，已被证明对肌萎缩侧索硬化和阿尔茨海默病的啮齿动物模型有效。据报道，这种环状六肽 (c[Arg-Trp-D-Cha-Pro-Orn]-Hca) 在溶液和固相合成中的线性肽组装和环化反应的产率相对较低。在尝试重现固相方法的过程中，遇到了灾难性的取代损失，这可以通过使用 2-氯三苯甲基树脂来避免或减少。同样，环化反应可以通过使用高稀释度的 FDPP（五氟苯基二苯基次膦酸盐）（高达 80% 的纯化产率）得到显着改善。这两种改进都是通过市售产品实现的。