The first synthesis of the cyclic octapeptide, cyclogossine B, has been achieved, confirming the reported structure of this natural product. Cyclization of a linear precursor containing a cysteine-derived thiazolidine as a traceless turn-inducer occurred in significantly higher yields than cyclization of the analogous alanine-containing precursor under identical conditions. Deprotection of the thiazolidine followed by desulfurization provided cyclogossine B in good overall yield, indicating that cysteine-derived pseudoprolines can be effectively used as traceless turn-inducers to facilitate the cyclization of small peptides.
首次合成了环状八肽环高辛 B,证实了已报道的这种天然产物的结构。在相同的条件下,含有半胱氨酸衍生的噻唑烷作为无痕转向诱导剂的线性前体的环化产率明显高于含有类似丙氨酸的前体的环化产率。先对噻唑烷进行脱保护,然后再进行脱硫处理,就可以得到总产率很高的环高辛 B,这表明半胱氨酸衍生的假脯氨酸可以有效地用作无踪转向诱导剂,促进小肽的环化。