A two-step strategy for the transition-metalfree CÀ H functionalization of arenes using unsymmetrical iodonium salts as versatile synthetic linchpins is presented. The key to the success of this strategy is the identification of the 3,5-dimethyl-4-isoxazolyl (DMIX) group as a superior dummy ligand, which enables not only site-selective CÀ H functionalization to afford unsymmetrical iodonium salts, but also highly selective aryl transfer during the subsequent metal-free coupling reaction. Both electron-rich and moderately electrondeficient arenes can be converted into the iodonium salts through CÀ H functionalization, allowing for diverse structural elaboration by metal-free CÀ N, CÀ C, CÀ S, and CÀ O coupling.

Nuclear magnetic resonance (NMR) spectroscopy has long been utilized as a classic method for chiral discrimination of enantiomers. However, its sensitivity limitations have hindered the detection of analytes at low concentrations. In this study, we present our efforts to overcome this challenge by employing chiral NMR probes that are labeled with a significant number of chemically equivalent 19F atoms. Specifically, we have designed and synthesized three chiral palladium pincer complexes, all of which are labeled with nonafluoro-tert-butoxy groups to enhance detectability. The recognition of enantiomers with the probe induces distinct changes in microenvironments, resulting in differential perturbations on the chemical shift of the 19F atoms in proximity. This method is applicable to the enantiodifferentiation of various amines, amino alcohols, and amino acid esters. The abundance of 19F atoms enables the detection of chiral analytes at low concentrations, which is otherwise challenging to achieve through traditional 1H NMR-based analysis. Two of the probes are constructed with asymmetric pincer ligands with structurally varied sidearms, allowing for facile manipulation of the chiral binding pocket. The C2 symmetrical probe possesses 36 equivalent 19F atoms, enabling the determination of enantiocomposition of samples with concentrations in the low micromolar range.

A two-step strategy for the transition-metalfree CÀ H functionalization of arenes using unsymmetrical iodonium salts as versatile synthetic linchpins is presented. The key to the success of this strategy is the identification of the 3,5-dimethyl-4-isoxazolyl (DMIX) group as a superior dummy ligand, which enables not only site-selective CÀ H functionalization to afford unsymmetrical iodonium salts, but also highly selective aryl transfer during the subsequent metal-free coupling reaction. Both electron-rich and moderately electrondeficient arenes can be converted into the iodonium salts through CÀ H functionalization, allowing for diverse structural elaboration by metal-free CÀ N, CÀ C, CÀ S, and CÀ O coupling.