Metal-Free C-H Functionalization via Diaryliodonium Salts with a Chemically Robust Dummy Ligand

A two-step strategy for the transition-metal-free C−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 C−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 electron-deficient arenes can be converted into the iodonium salts through C−H functionalization, allowing for diverse structural elaboration by metal-free C−N, C−C, C−S, and C−O coupling.

Recognition-Enabled Automated Analyte Identification Via 19F NMR

Nuclear magnetic resonance (NMR) is an indispensable tool for structural elucidation and noninvasive analysis. Automated identification of analytes with NMR is highly pursued in metabolism research and disease diagnosis; however, this process is often complicated by the signal overlap and the sample matrix. We herein report a detection scheme based on 19F NMR spectroscopy and dynamic recognition, which effectively simplifies the detection signal and mitigates the influence of the matrix on the detection. It is demonstrated that this approach can not only detect and differentiate capsaicin and dihydrocapsaicin in complex real-world samples but also quantify the ibuprofen content in sustained-release capsules. Based on the 19F signals obtained in the detection using a set of three 19F probes, automated analyte identification is achieved, effectively reducing the odds of misrecognition caused by structural similarity.