Mechanistic Basis for Regioselection and Regiodivergence in Nickel-Catalyzed Reductive Couplings.
Mechanistic Basis for Regioselection and Regiodivergence in Nickel-Catalyzed Reductive Couplings.
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DOI：
10.1021/acs.accounts.5b00096
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发表时间：
2015-06-16
影响因子：
18.3
通讯作者：
Montgomery, John
中科院分区：
文献类型：
--
作者：
Jackson, Evan P.;Malik, Hasnain A.;Sormunen, Grant J.;Baxter, Ryan D.;Liu, Peng;Wang, Henglin;Shareef, Abdur-Rafay;Montgomery, John
区域化学的控制是一个相当大的挑战，在发展的一系列广泛的催化过程。简单的π-组分如烯烃、炔烃、1，3-二烯和联烯是在区域选择性催化中呈现复杂性的许多种类的底物中的一种。考虑作为代表性实例的内炔，当两个取代基之间的空间和电子差异最小时，在炔的两个末端之间进行区分提出了很大的挑战。在炔取代基之间差异很大的情况下，克服这些偏见以获得与底物偏见所青睐的相反的区域异构体通常会带来更大的挑战。镍催化的不对称π-组分的还原偶联组成了一组反应，其中区域化学的控制呈现出具有挑战性但重要的目标。在我们的研究过程中，炔-炔还原偶联，互补的解决方案，在区域控制的挑战已经开发。通过仔细选择的配体和还原剂，以及更微妙的反应变量，如温度和浓度，有效的协议已被建立，允许高选择性的访问任一区域异构体的烯丙醇产品使用广泛的不对称炔。计算研究和评价反应动力学提供了一个了解的起源区域选择性控制。在所描述的各种程序中，配体-底物相互作用的发展起着关键作用，并且发现总体动力学描述在协议之间存在差异。合理改变的速率决定步骤中起着关键作用的区域化学逆转策略，并在一个实例中，两个可能的区域异构体的结果在一个单一的反应中被发现操作不同的动力学描述。有了这些机制信息，影响区域化学的经验因素就可以很容易地理解，更重要的是，这些见解提出了简单和可预测的实验变量，以实现所需的反应结果。因此，这些研究提出了一个详细的图片的影响，控制区域选择性在一个特定的催化反应，但他们也描绘了区域控制的策略，可以扩展到许多类的反应。这项工作提供了一个例子，说明如何洞察到催化过程的动力学和机制，可以合理化微妙的经验发现，并建议简单和合理的修改程序，以获得理想的反应结果。此外，这些研究提供了一个例证，说明有机合成中的重要挑战如何通过贱金属催化提供的新反应性来满足。在这种情况下，镍催化的使用不仅提供了一种廉价和可持续的催化方法，而且还实现了其他金属无法获得的独特反应模式。
The control of regiochemistry is a considerable challenge in the development of a wide array of catalytic processes. Simple π-components such as alkenes, alkynes, 1,3-dienes, and allenes are among the many classes of substrates that present complexities in regioselective catalysis. Considering an internal alkyne as a representative example, when steric and electronic differences between the two substituents are minimal, differentiating among the two termini of the alkyne presents a great challenge. In cases where the differences between the alkyne substituents are substantial, overcoming those biases to access the regioisomer opposite that favored by substrate biases often presents an even greater challenge. Nickel-catalyzed reductive couplings of unsymmetrical π-components make up a group of reactions where control of regiochemistry presents a challenging but important objective. In the course of our studies of aldehyde-alkyne reductive couplings, complementary solutions to challenges in regiocontrol have been developed. Through careful selection of the ligand and reductant, as well as the more subtle reaction variables such as temperature and concentration, effective protocols have been established that allow highly selective access to either regiosiomer of the the allylic alcohol products using a wide range of unsymmetrical alkynes. Computational studies and an evaluation of reaction kinetics have provided an understanding of the origin of the regioselectivity control. Throughout the various procedures described, the development of ligand-substrate interactions play a key role, and the overall kinetic descriptions were found to differ between protocols. Rational alteration of the rate-determining step plays a key role in the regiochemistry reversal strategy, and in one instance, the two possible regioisomeric outcomes in a single reaction were found to operate by different kinetic descriptions. With this mechanistic information in hand, the empirical factors that influence regiochemistry can be readily understood, and more importantly, the insights suggest simple and predictable experimental variables to achieving a desired reaction outcome. These studies thus present a detailed picture of the influences that control regioselectivity in a specific catalytic reaction, but they also delineate strategies for regiocontrol that may extend to numerous classes of reactions. The work provides an illustration of how insights into the kinetics and mechanism of a catalytic process can rationalize subtle empirical findings and suggest simple and rational modifications in procedure to access a desirable reaction outcome. Furthermore, these studies present an illustration of how important challenges in organic synthesis can be met by novel reactivity afforded by base metal catalysis. The use of nickel catalysis in this instance not only provides an inexpensive and sustainable method for catalysis, but also enables unique reactivity patterns not accessible to other metals.
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影响因子：
15
作者：
Liu, Peng;McCarren, Patrick;Cheong, Paul Ha-Yeon;Jamison, Timothy F.;Houk, K. N.
通讯作者：
Houk, K. N.
影响因子：
16.6
作者：
Bower, John F.;Kim, In Su;Patman, Ryan L.;Krische, Michael J.
通讯作者：
Krische, Michael J.
影响因子：
15
作者：
Miller ZD;Li W;Belderrain TR;Montgomery J
通讯作者：
Montgomery J
影响因子：
15
作者：
Boren, Brant C.;Narayan, Sridhar;Fokin, Valery V.
通讯作者：
Fokin, Valery V.
影响因子：
4.3
作者：
Liu, Peng;Krische, Michael J.;Houk, Kendall N.
通讯作者：
Houk, Kendall N.