Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions.
Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions.
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DOI：
10.1039/c7sc04675h
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发表时间：
2018-02-28
期刊：
影响因子：
8.4
通讯作者：
Kambe N
中科院分区：
文献类型：
--
作者：
Iwasaki T;Fukuoka A;Yokoyama W;Min X;Hisaki I;Yang T;Ehara M;Kuniyasu H;Kambe N
用实验和理论相结合的方法阐明了阴离子镍络合物促进C-C键形成反应的详细反应机理。我们描述了镍催化的烷基氟化物、芳基格氏试剂和两个1，3-丁二烯分子的四组分偶联反应的机理、取代基效应和选择性的来源，以及竞争交叉偶联反应。四组分偶联反应和交叉偶联反应都是由1，3-丁二烯的两个分子在Ni(0)上氧化二聚生成的阴离子镍络合物引发的，然后与芳基格氏试剂络合。烷基氟化物与阴离子镍络合物的γ-C形成C-C键，形成四组分偶联产物，而交叉偶联产物则通过Ni中心对烷基氟化物的亲核攻击而产生。这些步骤是整个催化循环的速率决定步骤和选择性决定步骤，在整个催化循环中，烷基氟的C-F键被镁离子而不是Li或锌离子激活。芳基格氏试剂的邻位取代基抑制了交叉偶联反应，导致四组分产物的选择性形成。ATE络合物的晶体结构表征和密度泛函理论计算清楚地证明了邻位取代基的这种空间效应。详细讨论了芳基格氏试剂的对位取代基对选择性和反应速率的电子效应。目前的机理研究提供了对阴离子络合物的新见解，阴离子络合物被认为是催化转化的关键中间体，尽管在许多情况下还没有建立详细的机理，并展示了它们作为C-C键形成反应的有希望的中间体的合成用途，为开发高效和直接的多组分反应提供了有用的信息。
The detailed reaction mechanism of anionic Ni complex-promoted C–C bond forming reactions was clarified by experimental and theoretical methods. We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C–C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C–F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C–C bond forming reactions, providing useful information for developing efficient and straightforward multicomponent reactions.
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影响因子：
15
作者：
Hatakeyama, T;Ito, S;Nakamura, B
通讯作者：
Nakamura, B
影响因子：
2.8
作者：
Gschwind, RM;Rajamohanan, PR;Boche, G
通讯作者：
Boche, G
影响因子：
15
作者：
Erickson, Lucas W.;Lucas, Erika L.;Jarvo, Elizabeth R.
通讯作者：
Jarvo, Elizabeth R.
影响因子：
4
作者：
AKUTAGAWA, S
通讯作者：
AKUTAGAWA, S
影响因子：
2.3
作者：
BAKER, R;NOBBS, MS;WINTON, PM
通讯作者：
WINTON, PM