Liu Lei, Du Luan, Li Baosheng
School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China.
Chem Commun (Camb). 2023 Jan 17;59(6):670-687. doi: 10.1039/d2cc04805a.
Medium-ring systems, which constitute a class of structurally intriguing and biologically important molecules, are present in many natural products and pharmaceuticals. However, the construction of these skeletons tends to be difficult because of the torsional strain of the medium-sized ring, and control of the selectivity is also challenging in these flexible skeletons. Electrocyclization is one of the most straightforward methods to construct medium-sized rings and this process typically proceeds in a stereospecific manner, resulting in the stereo-controlled formation of two neighboring stereocenters. At present, there are few studies on 8π electrocyclization, mainly focusing on the synthesis of small molecules, while the applications in the synthesis of functional materials and biological contexts are rare. This feature article highlights recent advances, from 2000 to 2022, in the 8π electrocyclization reaction. This study is organized into four sections based on the size/composition of the target ring, including the synthesis of aza-seven-membered, cycloheptene, cyclooctene and bicyclo[4,2,0]octane frameworks. We expect that this feature article will provide beneficial guidance for the selective construction of medium-ring skeletons.
中环体系是一类结构引人入胜且具有重要生物学意义的分子，存在于许多天然产物和药物中。然而，由于中环的扭转应变，这些骨架的构建往往很困难，并且在这些灵活的骨架中控制选择性也具有挑战性。电环化是构建中环最直接的方法之一，这个过程通常以立体专一的方式进行，导致两个相邻立体中心的立体控制形成。目前，关于8π电环化的研究很少，主要集中在小分子的合成上，而在功能材料合成和生物学背景中的应用则很少见。这篇专题文章重点介绍了2000年至2022年期间8π电环化反应的最新进展。本研究根据目标环的大小/组成分为四个部分，包括氮杂七元环、环庚烯、环辛烯和双环[4,2,0]辛烷骨架的合成。我们希望这篇专题文章将为中环骨架的选择性构建提供有益的指导。
