Mechanistic Investigations and Substrate Scope Evaluation of Ruthenium-Catalyzed Direct sp3 Arylation of Benzylic Positions Directed by 3-Substituted Pyridines
摘要:
A highly efficient direct arylation process of benzylic amines with arylboronates was developed that employs Ru catalysis. The arylation takes place with greatest efficiency at the benzylic sp(3) carbon. If the distance to the activating aryl ring is increased, arylation is still possible but the yield drops significantly. Efficiency of the CH activation was found to be significantly increased by use of 3-substituted pyridines as directing groups, which can be removed after the transformation in high yield. Calculation of the energy profile of different rotamers of the substrate revealed that presence of a substituent in the 3-position favors a conformation with the CH2 group adopting a position in closer proximity to the directing group and facilitating C-H insertion. This operationally simple reaction can be carried out in argon atmosphere as well as in air and under neutral reaction conditions, displaying a remarkable functional group tolerance. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.
Ruthenium(0)-Catalyzed sp3 C–H Bond Arylation of Benzylic Amines Using Arylboronates
摘要:
A Ru-catalyzed direct arylation of benzylic sp(3) carbons of acyclic amines with arylboronates is reported. This highly regioselective and efficient transformation can be performed with various combinations of N-(2-pyridyl) substituted benzylamines and arylboronates. Substitution of the pyridine directing group in the 3-position proved to be crucial in order to achieve high arylation yields. Furthermore, the pyridine directing group can be removed in high yields via a two-step protocol.
Suzuki–Miyaura Coupling of Simple Ketones via Activation of Unstrained Carbon–Carbon Bonds
作者:Ying Xia、Jianchun Wang、Guangbin Dong
DOI:10.1021/jacs.8b02462
日期:2018.4.25
Here, we describe that simple ketones can be efficiently employed as electrophiles in Suzuki-Miyauracoupling reactions via catalytic activation of unstrained C-C bonds. A range of common ketones, such as cyclopentanones, acetophenones, acetone and 1-indanones, could be directly coupled with various arylboronates in high site-selectivity, which offers a distinct entry to more functionalized aromatic
在这里,我们描述了通过催化激活无张力的 CC 键,简单的酮可以在 Suzuki-Miyaura 偶联反应中有效地用作亲电子试剂。一系列常见的酮,如环戊酮、苯乙酮、丙酮和1-茚满酮,可以直接与各种芳基硼酸酯以高位点选择性偶联,这为获得更多功能化的芳香酮提供了独特的途径。初步机理研究表明酮 α-CC 键通过氧化加成断裂。
First selective direct mono-arylation of piperidines using ruthenium-catalyzed C–H activation
作者:Maria C. Schwarz、Navid Dastbaravardeh、Karl Kirchner、Michael Schnürch、Marko D. Mihovilovic
DOI:10.1007/s00706-013-0947-1
日期:2013.4
A Ru-catalyzed mono-arylation in alpha-position of saturated cyclic amines is reported employing a C-H activation protocol. Substitution of the pyridine directing group with a bulky group, e.g., trifluoromethyl in the 3-position, proved to be crucial to avoid bis-arylation. This highly selective transformation can be performed with different amines and arylboronate esters. Additionally, the directing group can be cleaved, taking advantage of an unprecedented detrifluoromethylation reaction.
Mechanistic Investigations and Substrate Scope Evaluation of Ruthenium-Catalyzed Direct sp<sup>3</sup> Arylation of Benzylic Positions Directed by 3-Substituted Pyridines
作者:Navid Dastbaravardeh、Karl Kirchner、Michael Schnürch、Marko D. Mihovilovic
DOI:10.1021/jo302547q
日期:2013.1.18
A highly efficient direct arylation process of benzylic amines with arylboronates was developed that employs Ru catalysis. The arylation takes place with greatest efficiency at the benzylic sp(3) carbon. If the distance to the activating aryl ring is increased, arylation is still possible but the yield drops significantly. Efficiency of the CH activation was found to be significantly increased by use of 3-substituted pyridines as directing groups, which can be removed after the transformation in high yield. Calculation of the energy profile of different rotamers of the substrate revealed that presence of a substituent in the 3-position favors a conformation with the CH2 group adopting a position in closer proximity to the directing group and facilitating C-H insertion. This operationally simple reaction can be carried out in argon atmosphere as well as in air and under neutral reaction conditions, displaying a remarkable functional group tolerance. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.
Ruthenium(0)-Catalyzed sp<sup>3</sup> C–H Bond Arylation of Benzylic Amines Using Arylboronates
作者:Navid Dastbaravardeh、Michael Schnürch、Marko D. Mihovilovic
DOI:10.1021/ol300627p
日期:2012.4.6
A Ru-catalyzed direct arylation of benzylic sp(3) carbons of acyclic amines with arylboronates is reported. This highly regioselective and efficient transformation can be performed with various combinations of N-(2-pyridyl) substituted benzylamines and arylboronates. Substitution of the pyridine directing group in the 3-position proved to be crucial in order to achieve high arylation yields. Furthermore, the pyridine directing group can be removed in high yields via a two-step protocol.