Theoretical Investigation of Regioselectivity in the Rh-Catalyzed Coupling Reaction of 3-Phenylthiophene with Styrene
Theoretical Investigation of Regioselectivity in the Rh-Catalyzed Coupling Reaction of 3-Phenylthiophene with Styrene
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Rh 催化 3-苯基噻吩与苯乙烯偶联反应区域选择性的理论研究
DOI：
10.1002/ejoc.201900110
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发表时间：
2019
影响因子：
2.8
通讯作者：
Kawauchi Susumu
中科院分区：
文献类型：
--
作者：
Hayashi Yoshihiro;Satoh Tetsuya;Miura Masahiro;Kawauchi Susumu
用量子化学方法研究了Rh催化的3-苯基噻吩苯与苯乙烯偶联反应的区域选择性。以往的实验研究表明，在偶联反应中，苯乙烯选择性地偶联到苯基噻吩苯基上。在这项工作中，通过理论计算对可能的反应路径进行了评估，发现最合理的催化顺序如下：(1)Rh催化剂裂解苯基和噻吩基上的两个C-H键，生成一个五元罗达环中间体。(2)苯环苯基上的C-Rh键上插入了苯乙烯。(3)发生β-氢消除反应，生成2‘-烯基-3-苯基噻吩环。自然键轨道分析结果表明，决定产物的关键步骤，即苯乙烯优先插入苯侧(2)，是由于五元环中间体的苯基和噻吩基之间的π电子密度不同而发生的。
The regioselectivity of the Rh‐catalyzed coupling reaction of 3‐phenylthiophene with styrene was investigated by quantum chemistry calculations. Previous experimental studies showed that styrene selectively couples to the phenyl moiety of the phenylthiophene in the coupling reaction. In this work, possible reaction paths for the coupling were evaluated using theoretical calculations, and the most energetically reasonable catalytic sequence was found to be the following: (1) The Rh catalyst cleaves two C–H bonds on the phenyl and thiophene moieties, leading to a five‐membered rhodacycle intermediate. (2) Styrene is inserted into the C–Rh bond on the phenyl group of the rhodacycle. (3) Then, β‐hydrogen elimination occurs to form 2′‐alkenylated 3‐phenylthiophene. Natural bond orbital analysis results suggest that the key product‐determining step, i.e., the preferential insertion of styrene to the phenyl side (2), occurs due to the difference in π‐electron density between the phenyl and thienyl groups of the five‐membered rhodacycle intermediate.