Rhodium-catalyzed atroposelective C-H fluoroallylation of heteroarenes with gem-difluorocyclopropanes

Atroposelective C-H bond allylation represents an efficient and sustainable strategy toward construction of axially chiral functionalized biaryls. Yet existing systems are limited in reaction patterns using olefins and allyl ethers/esters. The lack of synthetic methods is ascribed to limited mechanistic pathways underlying such transformations. Reported herein is Rh(i)-catalyzed stereoconvergent axially chiral C-H fluoroalkylation of non-electron-rich arenes using racemic gem-difluorocyclopropanes as bifunctional allyl precursors, which provides biaryls integrating an allyl moiety and a fluorine atom. Mechanistic studies reveal a Rh(i)/Rh(iii) oxidative addition-reductive elimination cycle involving C-H activation, β-F elimination, and rapid epimerization of the chiral axis, enabling selective reductive elimination to afford the axially chiral biaryl with high regio- and enantioselectivity. A representative product exhibits circularly polarized luminescence (CPL), highlighting the potential for high-performance chiral optoelectronic applications.