Sulfenimides disulfides

The direct electrosynthesis of S—N bonds from disulfides and amines has been shown to occur through a reaction of the amine with the oxidized disulfide being a strong electrophile. In contrast to the results, the cross-coupling of phthahmide (16) with disulfide does not proceed in a direct electrolysis. However, the electrosynthesis of sulfenimides (17) can be achieved by a [Br]" "-mediated cross-coupling reaction of imides with disulfides (Scheme 7). The electrolysis of a mixture of (16) and dicyclohexyl disulfide in an MeCN-NaBr-(Pt) system affords... 

Bromide and iodide ions are not only effective as redox catalyst in the indirect electrochemical formation of carbon-hetero atom bonds but also of hetero-hetero atom bonds. Thus, the nitrogen-sulfur bond in sulfenimides (Eq. (53) Table 4, No. 33) and sulfenimines (Eq. (54) Table 4, No. 34) can be generated. The electrogenerated active bromine species forms a positively polarized sulfenyl intermediate from disulfides. 

The desulfurization of organosulfur compounds with trivalent organophospho-rus compounds has been studied for more than four decades [118]. A variety of such reagents has been used to convert disulfides to monosulfides, trisulfides to disulfides or monosulfides, /3-keto sulfides to ketones, and sulfenimides to amines. They have also been used to remove sulfur from thioethers, thiols, and organometallic dithiocarboxylates, and oxygen from sulfones. 

Independent experiments at Farmitalia s showed that direct cyclization to the hydroxyethyl-substituted 2-thiacephem 382 occurred when the Kamiya disulfide 381a was allowed to react with a hydrosulfide salt, e.g. NaSH, although immediate removal of the reagent (partition between water and an organic solvent) was necessary to avoid extensive degradation of the product [209]. Similar results were obtained on thiosulfonate 381b and sulfenimide 381c. 

Electrochemical oxidation and reduction of het-ero atom compounds, such as N, S, and P compounds, has been intensively studied and utilized for synthesis of many fine chemicals [1-4]. Electrooxidative S-S, S-N, S-P, and N-P bond formation is performed successfully by electrolysis of thiols, disulfide/amine, disulfide/phosphate, amine/ phosphate, and so on, affording useful chemicals, e.g., thiuram disulfide [17], sulfenamide [18], sulfenimides [19], phosphorothiolates [20], phosphoramidate [21], and so on. For instance, cross-coupling of phthalimide and dicyclohexy disulfide is performed by electrolysis in acetonitrile containing a catalytic amount of sodium bromide under a ccaistant apphed voltage (3 V, 0.7-0.9 V vs. SCE) to afford N-(cyclohexylthio)phthalimide, an important prevulcanization inhibitor in the rubber industry, in quantitative yield [19] (Fig. 4). 

Without additional reagents Sulfenimides from disulfides... 

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