Sulfinamidines and sulfinimidate esters are important S(IV) aza-sulfur compounds containing S(=N)—N and S(=N)—O motifs. Developing modular methods from readily available sulfenamides is valuable for expanding the chemistry of high-valent sulfur compounds. Herein, we report an iodide/peroxide-promoted oxidative transformation of sulfenamides for the N/O-divergent synthesis of sulfinamidines and sulfinimidate esters. For oxidative amination, sulfenamides were reacted with amines in the presence of tetrabutylammonium iodide (TBAI) and tert-butyl hydroperoxide (TBHP) in EtOAc at room temperature for 15 h, affording a series of N-acyl sulfinamidines through S—N bond formation. For esterification, sulfenamides were treated with tetramethylammonium iodide (TMAI) and cumene hydroperoxide (CHP) in MeOH at 60 ℃ for 5 h to give the corresponding sulfinimidate esters through S—O bond formation. In selected cases, TMAI/TBHP conditions also promoted the esterification efficiently. This transition-metal-free protocol is operationally simple and shows good compatibility with aryl, alkyl, naphthyl, heteroaryl, and acyl-substituted sulfenamides, as well as primary amines, cyclic secondary amines, acyclic secondary amines, and structurally complex amines. The desired products were obtained in up to 96% yield, and both the amination and esterification reactions could be performed on millimole scale, demonstrating the synthetic practicality of the method. Mechanistic studies were carried out to probe the reaction pathway. Addition of butylated hydroxytoluene (BHT) or 2,2,6,6-tetramethylpiperidinooxy (TEMPO) strongly inhibited both transformations and led to substantial recovery of the sulfenamide starting materials. HRMS analysis detected sulfilimidoyl-related, morpholine-related, and methoxy-related radical adducts, suggesting that both sulfenamides and the external N/O nucleophiles may participate in radical processes. In addition, N-iodosuccinimide (NIS)-mediated control reactions afforded both amination and esterification products, supporting the possible involvement of iodinated high-valent sulfur intermediates. These results indicate that the reaction may proceed through a dual radical/polar pathway involving radical oxidative activation, possible radical coupling, and nucleophilic trapping of electrophilic sulfur species. This work provides a new oxidative platform for the synthesis of high-valent aza-sulfur compounds from sulfenamides.

Key words: sulfenamides, sulfinamidines, sulfinimidate esters, iodide/peroxide, N/O-divergent synthesis