Modern drug discovery faces numerous challenges during the course of hit selection and lead generation. One of the most prevalent techniques for lead generation and optimization is the systematic use of bioisosteres. For example, sulfilimines, which are monoaza analogues of sulfoxides, have emerged as valuable bioisosteres of sulfur-containing functional groups. In addition, sulfilimines have been used in medicinal chemistry due to the potential ease of modulation of their physicochemical properties, such as their acidity/basicity and hydrogen-bond-donating/-accepting capabilities. Moreover, sulfilimines are also versatile intermediates and reagents for the synthesis of sulfoximines, sulfondiimines, and nitrogen heterocycles. Furthermore, in 2009, Hudson et al. discovered a naturally occurring sulfilimine (S=N) bond in type IV collagen. The stability and biocompatibility of S=N bonds are the foundation for their applications in related areas of chemical biology. The unique properties and various biological activities of sulfilimines have inspired research devoted to their synthesis.

Recently, Qingmin Wang’s group have developed a method both for site-selective aromatic C–H sulfilimination reaction of aryl sulfonium salts and for aryl radical–mediated sulfilimination reactions of alkyl iodides by means of synergetic photoredox and copper catalysis. This mild, operationally simple method has a broad substrate scope and can readily be scaled up under continuous-flow conditions. Moreover, we demonstrated the utility of the method by synthesizing and functionalizing some structurally complex bioactive molecules. Late-stage introduction of sulfiliminyl motifs provides an important method for quickly generating molecular diversity and avoiding the need to preserve labile organosulfur moieties through multistep synthetic sequences. Against the backdrop of increasing interest in research on radical chemistry, the novel synthetic approach reported herein rapidly and efficiently transforms aryl or alkyl radicals into sulfilimines and can be expected to facilitate research in chemical biology and drug discovery by allowing for the preparation of structurally diverse libraries of sulfilimines. Relevant achievements were published in ACS Catal., 2025. DOI: 10.1021/acscatal.5c00082.