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The one‐pot synthesis of λ4‐dibenzothiophen‐5‐imino‐N‐dibenzothiophenium triflate (1) in multigram scale is reported. This compound reacts with Rh2(esp)2 (esp=α,α,α′,α′‐tetramethyl‐1,3‐benzenedipropionic acid) generating a Rh‐coordinated sulfonitrene species, which is able to transfer the electrophilic nitrene moiety to olefins. When indenes are used as substrates, isoquinolines are obtained in good yields. We assumed that after formation of the corresponding N‐sulfonio aziridine, a ring expansion occurs via selective C−C bond cleavage and concomitant elimination of dibenzothiophene. Unexpectedly, a similar protocol transforms 1‐arylcyclobutenes into 1‐cyano‐1‐arylcyclopropanes. Our calculations indicate that aziridination is not favored in this case; instead, sulfilimine‐substituted cyclobutyl carbocations are initially formed, and these evolve to the isolated cyclopropanes via ring contraction. Both procedures are operationally simple, tolerate a range of functional groups, including oxidation‐sensitive alcohols and aldehydes, and enable the convenient preparation of valuable 15N‐labelled products. These results demonstrate the potential of 1 to provide alternative pathways for the selective transfer of N‐atoms in organic molecules. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis and reactivity of a new sulfonium salt that can transfer a sulfonitrene unit to C=C double bonds. The salt was synthesized on a large scale and is stable in air and water. It was used in two different transformations, expanding indenes to isoquinolines and contracting arylcyclobutenes to cyanocyclopropanes. The reagent is versatile and can tolerate various functional groups, making it a useful tool in skeletal editing. The authors acknowledge funding and provide supporting information for further details. [Extracted from the article]