Sulfondiimines: synthesis, derivatisation and application.

Sulfondiimines are aza-analogues of sulfones and sulfoximines. In contrast to the latter two compound classes, sulfondiimines are rare in the chemical literature. Although a full understanding of the stability and reactivity of sulfondiimines is wanting, sulfondiimines have recently been recognized as novel bioisosteres for carbonyl moieties enabling expansion of the well-known portfolio of pharmaceutically relevant compounds. In this review, we briefly summarize the structure and stability of sulfondiimines and then focus on syntheses and derivatisations of these interesting compounds with sulfur-nitrogen core units. Furthermore, their use in heterocyclic chemistry and recent applications as bioactive compounds are presented.

Synthesis of N-Monosubstituted Sulfondiimines by Metal-free Iminations of Sulfilimium 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 1 H NMR spectroscopy, ESI mass spectrometry, and crystallographic analysis we propose a direct amination from PhINNs and a reaction path via a cationic iodonitrene.

Acid-Mediated Imidazole-to-Fluorine Exchange for the Synthesis of Sulfonyl and Sulfonimidoyl Fluorides.

Sulfur(VI) fluoride motifs are important entities in organic chemistry. Typically, their syntheses involve the corresponding chlorides, which are often difficult to prepare and characterized by a poor storability due to the inherently weak S-Cl bond. Here, a single-step procedure for the preparation of sulfur(VI) fluorides starting from sulfonyl imidazoles as stable S(VI) reservoirs is described. By using a simple combination of AcOH and potassium bifluoride (KF2H), an imidazole-to-fluorine exchange furnishes a variety of sulfonyl, sulfonimidoyl, sulfoxyl, and sulfamoyl fluorides in good to excellent yields.