Electrogenerated Acid (EGA)-catalyzed Addition of Diaryl Disulfides to Carbon–Carbon Multiple Bonds

Abstract

Addition of diaryl disulfides to carbon–carbon multiple bonds was achieved with a catalytic amount of an electrogenerated acid (EGA), which was produced by the electrolysis of Bu4N+B(C6F5)4−/CH2Cl2. The anti-addition products of two ArS groups across the carbon–carbon multiple bond were obtained in good yields.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…Catalytic protocols have also been developed wherein substoichiometric amounts of the ArS + equivalent initiates a cation chain mechanism. 507,508 This “ArS + cation pool” also found utility in the functionalization of arenes, allyl silanes, enol ethers, and ketene acetals (Figure 33B, middle); 511 moreover, it could be used to induce oxocarbenium formation through reaction with thioacetals (Figure 33B, right). 512–514 This process has found application in glycosylation chemistry where efficient protocols with flow reactors have been detailed.…”

“…Similarly, the anodic oxidation of aryl disulfides at low temperatures allowed the accumulation of highly electrophilic ArS + equivalent which could form episulfonium intermediates upon reaction with olefins or alkynes (Figure B, left). − The thiirane could be opened directly with hard nucleophiles such as fluorides or alkoxides. Nevertheless, due to the presence of disulfides in solution, treatment of the episulfonium with soft nucleophiles led to the formation of vicinal disulfides instead.…”

“…Nevertheless, due to the presence of disulfides in solution, treatment of the episulfonium with soft nucleophiles led to the formation of vicinal disulfides instead. Catalytic protocols have also been developed wherein substoichiometric amounts of the ArS + equivalent initiates a cation chain mechanism. , This “ArS + cation pool” also found utility in the functionalization of arenes, allyl silanes, enol ethers, and ketene acetals (Figure B, middle); moreover, it could be used to induce oxocarbenium formation through reaction with thioacetals (Figure B, right). − This process has found application in glycosylation chemistry where efficient protocols with flow reactors have been detailed. , Furthermore, the “ArS + cation pool” was utilized (in catalytic amounts) to initiate olefin cyclization reactions, forming both heterocyclic and carbocyclic rings (Figure C). , …”

Glycosylation of a Newly Functionalized Orthoester Derivative

“…We reported the synthesis and reaction of the orthoester 1 (Figure 1), which could be purified by silica gel column chromatography and kept for one month at room temperature [14]. Upon glycosylation with appropriate alcohols in the presence of the OPEN ACCESS electrogenerated acid (EGA) [15][16][17][18][19][20], which is considered to be anhydrous HClO 4 produced by anodic oxidation of cyclohexanol and Bu 4 NClO 4 , the corresponding glycosides were produced in high (primary OH) to moderate (secondary OH) yields, even on tertiary OH groups [14]. Upon comparison with Lewis acids and Brønsted acids, EGA provided better results in glycosylation reactions.…”

Development of Glycosylation Using the Glucopyranose 1,2-Orthobenzoate under Electrochemical Conditions

“…Thus, the glycosylation reactions were promoted by an electrochemically generated acid (EGA), which might be anhydrous HClO 4 , produced via the reaction of the proton generated at the anode, and ClO 4 – from the supporting salt. To understand the effect of the EGA, glycosylation of 2F was carried out by addition of the EGA, prepared in advance by using electrolysis conditions (Table , entries 1–6) in a divided cell to avoid the effect of the amine generated by reduction of a quaternary ammonium cation at the cathode. , EGA, carrying the ClO 4 anion (entries 1, 2), effected better results than others (entries 3–6). In comparison with Lewis and Brønsted acids (entries 7–10), even a catalytic amount of EGA (entry 2) promoted a more effective reaction (Table ).…”