Nickel-Catalyzed Amination of Aryl Pivalates by the Cleavage of Aryl CO Bonds
作者:Toshiaki Shimasaki、Mamoru Tobisu、Naoto Chatani
DOI:10.1002/anie.200907287
日期:2010.4.6
Catalytic amination: The title reaction demonstrates the use of aryl carboxylates as suitable electrophilic coupling substrates in catalytic amination reactions. N‐heterocyclic carbene ligands and NaOtBu promote the amination of aryl pivalates through the cleavage of normally unreactive aryl carbon–oxygen bonds (see scheme; cod=cyclooctadiene).
催化胺化:标题反应表明在催化胺化反应中使用芳基羧酸盐作为合适的亲电子偶联底物。N-杂环卡宾配体和NaO t Bu通过裂解通常不活泼的芳基碳氧键来促进新戊酸芳基的胺化(参见方案; cod =环辛二烯)。
Donor–Acceptor Fluorophores for Energy-Transfer-Mediated Photocatalysis
triplet state) via a combined photochemical and transient absorption spectroscopic study. We found that the energy order between 1CT (charge transfer singlet state) and 3LE dictates the accessibility of 3LE/3CT for EnT, which can be effectively engineered by varying solvent polarity and D-A character to depopulate 3LE and facilitate EnT from the chemically more tunable 3CT state for photosensitization
三重态-三重态能量转移 (EnT) 是光催化中的基本活化途径。在这项工作中,我们报告了基于 EnT 的光催化反应中咔唑 - 氰基苯供体 - 受体(DA)荧光团的三重激发态的机械起源,并证明了控制 3LE(局部激发三重态)可及性的关键因素和通过结合光化学和瞬态吸收光谱研究的 3CT(电荷转移三重态)。我们发现 1CT(电荷转移单线态)和 3LE 之间的能量顺序决定了 EnT 3LE/3CT 的可及性,这可以通过改变溶剂极性和 DA 特征来有效地设计,以减少 3LE 的数量并促进 EnT 从化学更可调的 3CT光敏状态。遵循上述设计原则,鉴定了一种具有强 DA 特性和弱氧化还原电位的新型 DA 荧光团,该荧光团对 Ni(II) 催化的羧酸和芳基卤化物的交叉偶联表现出高效率,具有广泛的底物范围和高选择性。我们的结果不仅为 DA 荧光团的 EnT 机制提供了关键的基本见解,而且还确立了其在 EnT
Oxidative Addition of Aryl Electrophiles to a Prototypical Nickel(0) Complex: Mechanism and Structure/Reactivity Relationships
作者:Sonia Bajo、Gillian Laidlaw、Alan R. Kennedy、Stephen Sproules、David J. Nelson
DOI:10.1021/acs.organomet.7b00208
日期:2017.4.24
Detailed kinetic studies of the reaction of a model Ni0 complex with a range of aryl electrophiles have been conducted. The reactions proceed via a fast ligand exchange pre-equilibrium, followed by oxidativeaddition to produce either [NiIX(dppf)] (and biaryl) or [NiII(Ar)X(dppf)]; the ortho substituent of the aryl halide determines selectivity between these possibilities. A reactivity scale is presented
已经对模型 Ni0 络合物与一系列芳基亲电子试剂的反应进行了详细的动力学研究。反应通过快速配体交换预平衡进行,然后氧化加成生成 [NiIX(dppf)](和联芳基)或 [NiII(Ar)X(dppf)];芳基卤化物的邻位取代基决定了这些可能性之间的选择性。提出了一个反应性等级,其中一系列底物按照它们经历氧化添加的速率进行定量排序。氧化加成速率与原型交叉偶联反应中的转化率松散相关。在动力学实验中导致 NiI 产物的底物在催化条件下会产生更多的同源偶联产物。
Rhodium-catalyzed Borylation of Aryl and Alkenyl Pivalates through the Cleavage of Carbon–Oxygen Bonds
Rhodium-catalyzed borylation reactions of aryl and alkenyl pivalates, using a diboron reagent, via the cleavage of carbon–oxygen bonds have been developed. The inert nature of the pivalate moiety enables relatively complex aryl boronates to be synthesized via the tandem cross-coupling of carbon–halogen and carbon–oxygen bonds.
Organozinc-mediated direct cross-coupling under microwave irradiation
作者:Chun-Jing Li
DOI:10.1177/17475198211026479
日期:2021.9
direct cross-coupling reaction between (het)aryl pivalates/tosylates and di(het)arylzinc species in 2-methyltetrahydrofuran/N-methyl pyrrolidone (1:1), which occurs via C–O bond cleavage undermicrowaveirradiation. The reaction takes place smoothly in short reaction times without the addition of any catalyst or ligand. The reaction is suitable for a broad scope of substrates and exhibits good functional