C-F Bond Activation and C-H Bond Zincation of Fluoroarenes with Molecular Zinc Hydrides: Catalyst-Free and Palladium-Catalyzed Pathways

Herein, we report both catalyst-free and palladium-catalyzed C–F bond activation of pentafluoropyridine, C5F5N, using [DepLZnH]2 and DippLZnH, where (L ={(ArHN)(ArN) −C=N−C=(NAr) (NHAr); Dep =Ar =2,6-Et2−C6H3, Dipp =Ar =2,6-iPr2−C6H3}], leading to the formation of corresponding bis-guanidinate stabilized zinc fluoride complexes (Zn-1 and Zn-2). These species have been thoroughly characterized by standard spectroscopic methods. Further, we demonstrate a regioselective C–H zincation protocol for a series of fluoroarenes employing bis-guanidinate-supported zinc hydride complexes under both catalyst-free and Pd-catalyzed conditions. These transformations proceed under mild conditions and provide a wide range of bis-guanidinate zinc-aryl complexes in moderate to high yields with excellent ortho-selectivity, directed by fluorine substitution patterns. The resulting organozinc compounds are thoroughly characterized, including all standard spectroscopic techniques, and are well-suited for Negishi cross-coupling reactions, enabling efficient conversion of fluoroarenes into biaryl products (C-C bond formation). This work establishes bis-guanidinate zinc hydrides as versatile reagents for selective C–F bond activation and C–H functionalization in synthetic chemistry.