Selective Functionalization of Styrenes with Oxygen Using Different Electrode Materials: Olefin Cleavage and Synthesis of Tetrahydrofuran Derivatives

Oxidation Potential Gap (ΔEox ): The Hidden Parameter in Redox Chemistry

Oxidative biaryl coupling of aryls with different electronic features generally fails. However, this has not been systematically studied via theoretical analysis, and thus, the crucial factor governing coupling efficiency remains unclear. Herein, we propose that the "oxidation potential gap (ΔE_ox )" is a key parameter in predicting the efficiency of an intramolecular oxidative coupling reaction, with ΔE_ox defined as a difference in the oxidation potentials of the relevant aromatic rings. Our experimental and computational analyses revealed that the efficiency of an aromatic intramolecular coupling reaction correlates with the activation energy (ΔE^≠ ) of C-C bond formation of the radical cation intermediates. Furthermore, ΔE^≠ correlates with ΔE_ox . Therefore, we demonstrate the tuning of ΔE_ox by attaching cleavable extra electron-donating/-withdrawing groups, enabling the rational synthesis of a phenanthridone skeleton using aromatic rings with an electronic gap.

Electrochemical Oxidative Carbon-Atom Difunctionalization: Towards Multisubstituted Imino Sulfide Ethers

Ethers (C-O/S) are ubiquitously found in a wide array of functional molecules and natural products. Nonetheless, the synthesis of imino sulfide ethers, containing an N(sp² )=C(sp² )-O/S fragment, still remains a challenge because of its sensitivity to acid. Developed here in is an unprecedented electrochemical oxidative carbon-atom difunctionalization of isocyanides, providing a series of novel multisubstituted imino sulfide ethers. Under metal-free and external oxidant-free conditions, isocyanides react smoothly with simple and readily available mercaptans and alcohols. Importantly, the procedure exhibited high stereoselectivities, excellent functional-group tolerance, and good efficiency on large-scale synthesis, as well as further derivatization of the products.