Iodoarene-Catalyzed Stereospecific Intramolecular sp3 C–H Amination: Reaction Development and Mechanistic Insights
摘要:
A new strategy is reported for intramolecular Sp(3) C-H amination :under mild reaction conditions using iodoarene as catalyst and m-CPBA as oxidant. This C-H functionalization involving iodine(III) reagents generated in situ occurs readily at sterically hindered tertiary C-H bonds. DFT (M06-2X) calculations show that the preferred pathway involves an iodonium cation intermediate and proceeds via an energetically concerted transition state, through hydride transfer followed by the spontaneous C-N bond formation. ThiS leads to the experimentally observed amination at a chiral center without loss of stereo chemical information.
Reductive Coupling between C–N and C–O Electrophiles
作者:Rong-De He、Chun-Ling Li、Qiu-Quan Pan、Peng Guo、Xue-Yuan Liu、Xing-Zhong Shu
DOI:10.1021/jacs.9b05224
日期:2019.8.14
The cross-electrophile reaction is a promising strategy for C-C bond formation. Recent studies have focused mainly on reactions with organic halides. Here we report a coupling reaction between C-N and C-O electrophiles that demonstrates the possibility of constructing a C-C bond via C-N and C-O cleavage. Several reactions between benzyl/aryl ammonium salts and vinyl/aryl C-O electrophiles have been
交叉亲电反应是 CC 键形成的一个有前景的策略。最近的研究主要集中在与有机卤化物的反应上。在这里,我们报告了 CN 和 CO 亲电试剂之间的偶联反应,证明了通过 CN 和 CO 裂解构建 CC 键的可能性。已经研究了苄基/芳基铵盐和乙烯基/芳基 CO 亲电试剂之间的几种反应。初步机理研究表明,苄基铵是通过自由基机制活化的。
Efficient cross-coupling of aryl/alkenyl triflates with acyclic secondary alkylboronic acids
Aryl–secondary alkyl cross-coupling with aryl sulfonate esters as coupling partners remains a significant challenge. Efficient cross-coupling between aryl/alkenyl triflates and acyclicsecondary alkylboronic acids is realized for the first time to provide a series of sterically congested acyclicsecondary alkyl arenes/olefins in good to excellent yields. The employment of sterically bulky P,PO ligand L1/L2 is
Dynamic Kinetic Cross-Electrophile Arylation of Benzyl Alcohols by Nickel Catalysis
作者:Peng Guo、Ke Wang、Wen-Jie Jin、Hao Xie、Liangliang Qi、Xue-Yuan Liu、Xing-Zhong Shu
DOI:10.1021/jacs.0c12462
日期:2021.1.13
Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzylalcohols with (hetero)aryl electrophiles
Transition-Metal-Free C–C, C–O, and C–N Cross-Couplings Enabled by Light
作者:Wenbo Liu、Jianbin Li、Pierre Querard、Chao-Jun Li
DOI:10.1021/jacs.9b02684
日期:2019.4.24
and nitriles without the assistance of metal catalysts empowered by photoenergy. Control experiments reveal that among all common aryl electrophiles only aryl triflates are competent in these couplings whereas aryl iodides and bromides cannot serve as the coupling partners. DFT calculation reveals that once converted to the aryl radical cation, aryl triflate would be more favorable to ipso substitution
用于构建 CC、CO 和 CN 键的过渡金属催化交叉偶联已经彻底改变了化学科学。尽管取得了巨大的成就,但这些金属催化剂也存在一些问题,包括成本高、需要专门的配体、对空气和水分的敏感性以及所谓的“过渡金属残留问题”。不依赖于成熟的氧化加成、金属转移和还原消除机制范式的互补策略可能会消除所有这些与金属相关的问题。在此,我们表明芳基三氟甲磺酸酯可以与芳基三氟硼酸钾、脂肪醇和腈偶联,而无需借助光能赋能的金属催化剂。对照实验表明,在所有常见的芳基亲电试剂中,只有芳基三氟甲磺酸酯能够进行这些偶联,而芳基碘化物和溴化物不能作为偶联伙伴。DFT 计算表明,一旦转化为芳基自由基阳离子,芳基三氟甲磺酸酯将更有利于 ipso 取代。荧光光谱和循环伏安法研究表明,激发态丙酮和芳基三氟甲磺酸酯之间的相互作用对于这些偶联是必不可少的。预计本报告中的结果将为执行交叉耦合提供新的机会。荧光光谱和循环伏安法研究表明,激发态
Cationic Alkynyl Heck Reaction toward Substituted Allenes Using BobCat: A New Hybrid Pd(0)-Catalyst Incorporating a Water-Soluble dba Ligand
作者:Robynne K. Neff、Doug E. Frantz
DOI:10.1021/jacs.8b11759
日期:2018.12.19
cationic alkynyl Heck reaction between aryl triflates and alkynes to give substituted allenes is described. Key to the success of this method was the discovery and development of a new hybrid Pd(0)-catalyst, BobCat, that incorporates a water-soluble dba-ligand and biaryl phosphine ligand to provide substituted allenes in good yields under mild reaction conditions.