Recent Advances in Transition‐Metal‐Mediated Chelation‐ Assisted Sulfonylation of Unactivated C−H Bonds

Sulfones are ubiquitous structural motifs that frequently occur in pharmacologically active compounds and synthetic intermediates, and possess a wide range of biological properties. Due to their great value in pharmaceutical chemistry, material sciences and organic synthesis, considerable attention has been paid to the development of general and efficient methods for the synthesis of sulfones and their derivatives. Among the various methods developed, transition‐metal‐mediated (both catalytic and stoichiometric) direct sulfonylation through C−H activation has been considered as an attractive, efficient and atom‐economic strategy, which avoids the multistep preparation of preactivated starting materials and tolerates a wide variety of functional groups. This review is intended to comprehensively summarize the recent advances in the rapidly expanding area of sulfone synthesis via transition‐metal‐mediated C−H activation utilizing directing groups to govern the site selectivity. For clarity, this review is classified in line with the different types of transition metal catalysts used, including Pd, Ru, Rh, Cu, Ni, and Co. The reaction mechanisms are discussed and compared. Selected examples of substrates are listed as well, and a personal outlook is given at the end. magnified image