DOI: 10.1039/D0GC00591F
Abstract
采用三组分交叉耦合策略实现了富电子芳烃的C-H甲硫基化反应。以KSCN为支撑电解质和硫源，甲醇为甲基化试剂。该方案适用于各种（杂）芳香族化合物，如苯胺、苯甲醚和吲哚。反应在温和的条件下进行，无需任何金属催化剂、外源氧化剂和剧毒硫试剂。重要的是，这种电化学诱导的甲硫基化反应可以很容易地放大，效率很高（百度翻译）。
1. Reaction Optimization
2. Substrate Scope
3. Control Experiments
4. Proposed Mechanism
Conclusions
In conclusion, we have disclosed a facile and efficient C-H methylthiolation under electrochemical redox. Compared with the previously reported methods for the synthesis of aryl methyl sulfide, this electrochemical-based synthetic strategy can avoid the usage of external oxidants and transition metal catalysts. Various electron-rich aromatics exhibited good efficiencies for this transformation. On the other hand, it has been demonstrated that the cross-coupling of aryl-thiocyanate and methanol strategies can also efficiently synthesize sulfides. Importantly, these reactions can be performed on a gram scale with good reaction efficiency, and the sole necessary reagent in C-H methylthiolation is readily available thiocyanated salts. These advantages encourage us to have prospect towards industrialization. Further studies on using electrochemical oxidation and reduction to synthesize other sulfur-containing bioactive compounds are currently underway in our laboratory.
Experimental Section
In an oven-dried undivided three-neckedbottle (25 mL) equipped with a stir bar, electron-rich arene 1 (1 mmol),potassium thiocyanate 2a (5 mmol, 485.9 mg), H2O (1 mL) andCH3OH (9 mL) were combined and added. The bottle was equipped withplatinum plate (1 × 1 cm2 ) anode and nickel foam plate (2 × 3 cm2) cathode and was then charged with nitrogen. The reaction mixture was stirredand electrolyzed at a constant current of 5 mA under room temperature for 20 h.When the reaction was finished, CH3OH was removed with a rotaryevaporator, then the reaction mixture was washed with water and extracted withethyl acetate (10 mL × 3). The organic layers were combined, dried over Na2SO4,and concentrated. The pure product was obtained by flash column chromatographyon silica gel (petroleum: ethyl acetate = 5:1 - 10:1).
Reference
https://pubs.rsc.org/en/content/articlelanding/2020/gc/d0gc00591f
