This study has developed a method to prepare diastereo- and regio-selective indoline-fused 2,5-diketopiperazine scaffolds. The synthetic process involved an Ugi four-component reaction in which readily available starting materials were used and a metal-free intramolecular post-Ugi tandem consecutive 5-exo-trig/6-exo-dig cyclization under basic conditions. The plausible mechanism and substrate structures were elucidated by single-crystal X-ray diffraction analysis and supported by density functional theory calculations.

中文翻译：

---

在基本介导的串联连续环化中通过 Ugi-4CR 合成二氢吲哚融合的 2,5-二酮哌嗪支架

本研究开发了一种制备非对映和区域选择性二氢吲哚融合 2,5-二酮哌嗪支架的方法。合成过程涉及 Ugi 四组分反应，其中使用容易获得的起始材料和无金属分子内后 Ugi 串联连续5-exo-trig / 6-exo-dig在碱性条件下环化。通过单晶 X 射线衍射分析阐明了合理的机制和衬底结构，并得到了密度泛函理论计算的支持。