Mechanistic studies on the Pd-catalyzed direct C-H arylation of 2-substituted thiophene derivatives with arylpalladium bipyridyl complexes.
Mechanistic studies on the Pd-catalyzed direct C-H arylation of 2-substituted thiophene derivatives with arylpalladium bipyridyl complexes.
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DOI：
10.1002/asia.201101011
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发表时间：
2012-06
期刊：
影响因子：
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通讯作者：
M. Steinmetz;K. Ueda;S. Grimme;Junichiro Yamaguchi;Sylvia Kirchberg;K. Itami;A. Studer
中科院分区：
文献类型：
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作者：
M. Steinmetz;K. Ueda;S. Grimme;Junichiro Yamaguchi;Sylvia Kirchberg;K. Itami;A. Studer
研究了2-乙基噻吩和2-氯噻吩与PhPdI（bipy）配合物在化学计量条件下，以不同的刘易斯酸为添加剂，直接C-H苯基化生成相应的4-苯基或5-苯基噻吩衍生物。结果表明，反应发生通过相应的阳离子钯配合物（PhPdbipy（+））和抗衡阴离子决定的区域选择性。高层次的DFT计算表明，C-C键的形成发生通过碳钯化途径，而不是通过亲电钯化。这些计算给出了一些关于噻吩芳基化反应的区域选择性的指示。
Direct C-H phenylation of 2-ethylthiophene and 2-chlorothiophene with PhPdI(bipy) complex to form either the corresponding 4-phenyl or 5-phenylthiophene derivative is studied under stoichiometric conditions using various Lewis acids as additives. It is shown that reactions occur via the corresponding cationic Pd complex (PhPdbipy(+)) and that the counteranion determines the regioselectivity. High-level DFT calculations reveal that C-C bond formation occurs via a carbopalladation pathway and not via electrophilic palladation. These calculations give some indications regarding the regioselectivity of the thiophene arylation.