Access to Inherently and Centrally Chiral Calix[4]Arenes via Rhodium-Catalyzed C─H Activation and Insertion into Diverse Olefins and Alkynes.

Abstract

Inherently chiral calix[4]arenes are important scaffolds in asymmetric catalysis and sensing, yet their enantioselective synthesis remains challenging due to limited synthetic methodology and lengthy synthetic routes. By resorting to rhodium-catalyzed C─H activation of calix[4]arene-based carboxamides, atom-economical construction of inherently chiral calix[4]arenes has been realized with alkenes, alkynes, and 1,3-enynes as the coupling partner. Several classes of calix[4]arenes with inherent chirality (up to > 99% ee) and integrated inherent and central chirality (up to 97% ee, >20:1 dr) have been readily accessed under nearly unified conditions. Gram-scale synthesis and diverse downstream transformations demonstrated the scalability and broad utility of this methodology to access other calix[4]arene-fused heterocycles, such as isoquinoline and isoindolinone. Representative products exhibit promising fluorescence properties, suggesting potential applications in organic optoelectronics.