Ni触媒を利用したビスジメチルフェニルシリル亜鉛とアリールトリフレート類とのクロスカップリング反応

抄録

We found very interesting to design a route for the substitution of a phenolic hydroxyl for a halogen. The key step of this transformation is a novel cross-coupling reaction between zinc-silicon reagent and aryl triflates. We have chosen dimethylphenylsilyllithium as a source of silicon due to its ease of preparation from relatively cheap starting materials. An addition of ZnBr₂(0.5 equiv.) in THF gave silicon-zinc species. Screening of transition metal catalyst showed that Ni(dppp)Cl₂ affords fast and complete conversion of Aryl triflates into corresponding silicon derivate in excellent yield. The aryl dimethylphenylsilanes, obtained via new Ni-catalyzed cross-coupling reaction, can be easily transformed into the corresponding aryl iodides in high yields by treatment with 2 equiv. of iodine monochloride in dichloromethane at 0 °C. Furthermore, the obtained arylsilanes can be converted in good yields into the corresponding boronic esters.

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