Synthesis of N-Monosubstituted Sulfondiimines by Metal-free Iminations of Sulfiliminium Salts.

Abstract

Sulfondiimines are marginalized entities among nitrogencontaining 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 iminoiodanes (PhINR) in acetonitrile (MeCN) to furnish the corresponding sulfondiimines in yields up to 85% (25 examples). Valuable "free" NH-N'Hsulfondiimines 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/iminoiodane 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.