Potassium Trimethylsilanolate Enables Rapid, Homogeneous Suzuki−Miyaura Cross-Coupling of Boronic Esters
作者:Connor P. Delaney、Vincent M. Kassel、Scott E. Denmark
DOI:10.1021/acscatal.9b04353
日期:2020.1.3
Herein, a mild and operationally simple method for the Suzuki−Miyaura cross-coupling of boronicesters is described. Central to this advance is the use of the organic-soluble base, potassium trimethylsilanolate, which allows for a homogeneous, anhydrous cross-coupling. The coupling proceeds at a rapid rate, often furnishing products in quantitative yield in less than 5 min. By applying this method
Efficient Generation and Synthetic Applications of Alkyl‐Substituted Siloxycarbenes: Suppression of Norrish‐Type Fragmentations of Alkanoylsilanes by Triplet Energy Transfer
some alkanoylsilanes because Norrish-type fragmentations compete, which limit the synthetic utility of alkanoylsilanes as carbene precursors. In this study, generation of siloxycarbenes from alkanoylsilanes by visible-light-induced energytransfer was examined by using an Ir complex, [IrdF(CF3 )ppy}2 (dtbpy)]PF6 , and was successfully applied to the C-C coupling reactions with boronic esters or aldehydes
induced reductive elimination ( ORE) plays a critical role in the product-releasing C-C bond formation. Notably, we have demonstrated that ORE broadly operates with a series of half-sandwich d6 Ir(III)-, Rh(III)-, and Ru(II)-aryl complexes. We have described that the metal center oxidation of the isolable post-transmetalation intermediates by means of chemical- or electro-oxidation can readily deliver the
将 CH 键直接转化为 CC 键是传统交叉偶联反应的一种有前景的替代方法,从而产生了广泛的高效催化 CH 官能化反应。在催化 CC 键形成的基本阶段中,还原消除构成了催化循环的关键步骤,因此,已经进行了广泛的研究以促进这一过程。在这方面,金属转移后中间体金属中心的氧化将是一种有吸引力的方法。在此,我们探索了底物范围、催化剂系统和氧化工具,以证明氧化诱导还原消除 (ORE) 在释放产物的 CC 键形成中起着关键作用。值得注意的是,我们已经证明 ORE 广泛使用一系列半夹心 d6 Ir(III)-,Rh(III)-和Ru(II)-芳基配合物。我们已经描述了可分离的金属转移后中间体的金属中心氧化通过化学氧化或电氧化可以很容易地在还原消除后甚至在环境温度下提供所需的芳基化产物。计算研究描绘了还原消除的热力学,其中显示激活势垒随着中间体氧化态的增加而显着降低。我们还成功地在相应的 Rh-甲基复合物中证实了这种
Ruthenium(0)-Catalyzed C–H Arylation of Aromatic Imines under Neutral Conditions: Access to Biaryl Aldehydes
作者:Feng Hu、Michal Szostak
DOI:10.1021/acs.orglett.6b01738
日期:2016.9.2
The first ruthenium(0)-catalyzed C–H bond arylation of aromatic imines with arylboronates under neutral conditions is reported. This versatile method provides rapid access to a wide range of biaryl aldehydes that are difficult to assemble using traditional methods with high atom economy. A new hydrogen acceptor for Ru(0) arylation has been identified. This atom-economical strategy has potential for
The ruthenium-catalyzed reaction of aryl ethers having a carbonyl group at the ortho position to the ether group with organoboronates (R-B(OCH2CMe2CH2O), R = aryl, alkenyl, and alkyl) resulted in site-selective C-C bond formation. Among the transition metal complexes screened, the RuH2(CO)(PPh3)3 complex showed the highest activity. Several aromatic ketones having methoxy or phenoxy groups at the ortho
在醚基邻位具有羰基的芳基醚与有机硼酸酯 (RB(OCH2CMe2CH2O),R = 芳基、烯基和烷基) 的钌催化反应导致位点选择性 CC 键的形成。在筛选出的过渡金属配合物中,RuH2(CO)(PPh3)3 配合物显示出最高的活性。几种在邻位具有甲氧基或苯氧基的芳族酮也可用于该偶联反应。各种含有给电子(NMe2、OMe、甲基和乙烯基)和吸电子(F 和 CF3)基团的芳基硼酸酯与甲氧基酮反应,以高产率得到相应的偶联产物。