Synthesis of N‐Monosubstituted Sulfondiimines by Metal‐free Iminations of Sulfiliminium Salts

Sulfondiimines are marginalized entities among nitrogen‐containing organosulfur compounds, despite offering promising properties for applications in various fields including medicinal and agrochemical. Herein, we present a metal‐free and rapid synthetic procedure for the synthesis of N‐monosubstituted sulfondiimines that overcomes current limitations in their synthetic accessibility. Particularly, S,S‐dialkyl substrates, which are commonly difficult to convert by existing methods, react well with a combination of iodine, 1,8‐diazabicyclo[5.4.0]undec‐7‐en (DBU), and iminoiodinanes (PhINR) in acetonitrile (MeCN) to furnish the corresponding sulfondiimines in yields up to 85 % (25 examples). Valuable “free” NH‐N′H‐sulfondiimines can then be accessed by N‐deprotection under mild reaction conditions. Several experimental observations suggest a mechanistic pathway diverging from the common radical‐based iodine/iminoiodinane mechanism. Based on the experimental results in combination with data obtained by ¹H NMR spectroscopy, ESI mass spectrometry, and crystallographic analysis we propose a direct amination from PhINNs and a reaction path via a cationic iodonitrene.