Rapid Synthesis of Chiral Figure‐Eight Macrocycles Using a Preorganized Natural Product‐Based Scaffold
Tasuku Honda, Daiji Ogata, Makoto Tsurui, Satoshi Yoshida, Sota Sato, Takahiro Muraoka, Yuichi Kitagawa, Yasuchika Hasegawa, Junpei Yuasa, Hiroki Oguri
Abstract
Abstract Chiral D 2 ‐symmetric figure‐eight shaped macrocycles are promising scaffolds for amplifying the chiroptical properties of π‐conjugated systems. By harnessing the inherent and adaptable conformational dynamics of a chiral C 2 ‐symmetric bispyrrolidinoindoline (BPI) manifold, we developed an enantio‐divergent modular synthetic platform to rapidly generate a diverse range of chiral macrocycles, spanning from 14‐ to 66‐membered rings, eliminating the need for optical resolution. Notably, a 32‐membered figure‐eight macrocycle showed excellent circularly polarized luminescence (CPL: | g lum |=1.1×10 −2 ) complemented by a robust emission quantum yield (Φ fl =0.74), to achieve outstanding CPL brightness ( B CPL : ϵ ×Φ fl ×| g lum |/2=480). Using quadruple Sonogashira couplings, this versatile synthetic platform enables precise adjustments of the angle, distance, and length among intersecting π‐conjugated chromophores. Our synthetic strategy offers a streamlined and systematic approach to significantly enhance B CPL values for a variety of chiral D 2 ‐symmetric figure‐eight macrocycles.