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.

Strong Lewis acids are essential tools for a manifold of chemical procedures that aim to react weakly basic centres but their scalable deployment is severely limited by their costs and safety concerns. We report that dicationic relatives of guanidinium can be conveniently synthesised in a two-step one-pot procedure from tetramethylurea. Triflic anhydride is used to generate an isouronium intermediate. Substitution of the bound triflate with pyridines yield the dicationic tetramethyldiiminium bis(triflate) nucleophile adducts (TMDINu). Their proposed diiminium character is demonstrated by substituting pyridine from the corresponding adduct with other nucleophiles. The observation of a chelation effect in the 2,2’-bipyridine adducts supports Lewis acidic character of the diiminium π-system and flexibility towards accepting another bond. High fluoride, hydride, and oxide affinities are demonstrated, leading to their classification as soft and hard Lewis superacids. An example reaction is reported which shows that the tetramethyldiiminium bis(triflate) pyridine complex (TMDIPy) is more effective than conventional reagents in the activation of electron-poor amines for amide couplings.

Strong Lewis acids are essential tools for a manifold of chemical procedures, but their scalable deployment is limited by their costs and safety concerns. We report a scalable, convenient, and inexpensive synthesis of stable diiminium‐based reagents with a Lewis acidic carbon centre. Coordination with pyridine donors stabilises these centres; the 2,2’‐bipyridine adduct shows a chelation effect at carbon. Due to high fluoride, hydride, and oxide affinities, the diiminium pyridine adducts are promising soft and hard Lewis acids. They effectively produce acylpyridinium salts from carboxylates which can acylate amines to give amides and imides even from electronically intractable coupling partners.