Regioselective Synthesis of Trialkylpyrazines via Nickel-Catalyzed Negishi Cross-Coupling of Pyrazine Triflate
摘要:
A regioselective synthesis of trialkylpyrazines via nickel-catalyzed cross-coupling reaction of pyrazine triflate is reported. The 5-substituted 2,3-dimethylpyrazine derivatives including trail pheromone components of the ant Eutetramorium mocquerysi have been successfully synthesized in good yields by nickel-catalyzed Negishi cross-coupling reactions of pyrazine triflate mediated by alkyl and arylzinc halides.
N,N’-Bis(trimethylsilyl)-1,4-dihydropyrazines serves as starting materials for introducing alkyl groups into the parent pyrazine skeletons upon combined with aldehydes and nBu4NF as well as electron-deficient alkyl halides. In this reaction, activation of the trimethylsilyl moiety by fluoride is the key step for generating electron-rich silicate intermediates, while reduction of electron-deficient