Dehydrogenative Imination of Low-Valent Sulfur Compounds─Fast and Scalable Synthesis of Sulfilimines, Sulfinamidines, and Sulfinimidate Esters

Abstract

Herein, we describe an electrochemical pathway for the synthesis of sulfilimines, sulfoximines, sulfinamidines, and sulfinimidate esters from readily available low-valent sulfur compounds and primary amides or their analogues. The combination of solvents and supporting electrolytes together act both as an electrolyte as well as a mediator, leading to efficient use of reactants. Both can be easily recovered, enabling an atom-efficient and sustainable process. A broad scope of sulfilimines, sulfinamidines, and sulfinimidate esters with N-EWGs is accessed in up to excellent yields with broad functional group tolerance. This fast synthesis can be easily scaled up to multigram quantities with high robustness for fluctuation of current densities of up to 3 orders of magnitude. The sulfilimines are converted into the corresponding sulfoximines in an ex-cell process in high to excellent yields using electro-generated peroxodicarbonate as a green oxidizer. Thereby, preparatively valuable NH sulfoximines are accessible.

Overlooked aza-S(iv) motifs: synthesis and transformations of sulfinamidines and sulfinimidate esters

“…25 Similarly, in 2023 Waldvogel and co-workers described the electrochemical dehydrogenative imination of sulfenamide 6a towards sulfinamidine 15 (Scheme 6). 26 Although the scope of the method is limited to a single example, it is reasonable to envision that such protocol might proceed with other N,Nbisalkyl sulfenamides en route to N-tosyl sulfinamidines. In this case, the reaction is supposed to involve the oxidation of the starting sulfenamide and the consequent generation of a Recently, Bull and Armstrong disclosed the preparation of sulfinamidine 7i via the Rh 2 (esp) 2 -catalyzed nitrogen transfer to sulfenamide 6b with t-butyl carbamate (Scheme 7).…”

Progress in S–X Bond Formation by Halogen-Mediated Electrochemical Reactions

“…In 2023, Waldvogel and co-workers 68 realized an electrosynthesis of sulfilimines 74 , sulfoximines 75 , and their analogues from low-valent sulfur compounds 72 and primary amides 73 or their analogues (Scheme 29 ). The reactions were carried out in an undivided cell using glassy carbon as the anode and Pt foil as the cathode with NEt 4 Br as the supporting electrolyte at a current density of 50 mA/cm 2 .…”

Copper-Catalyzed Aerobic S-Amination of Sulfenamides for the Synthesis of Sulfinamidines

“…Nevertheless, the requirement for stoichiometric amounts of brominating reagents raises concerns about the environmental impact and cost-effectiveness of this approach. In addition to the aforementioned strategies, a few other methods have been reported in the literature with limited supporting documentation . Despite the array of existing methods, the development of efficient, sustainable, and widely applicable synthetic strategies for producing sulfinamidines is still a necessity.…”