Rhodium(III) and Hexabromobenzene-A Catalyst System for the Cross-Dehydrogenative Coupling of Simple Arenes and Heterocycles with Arenes Bearing Directing Groups
can be used as the cooxidant/catalyst modifier for the [RhIIICp*]‐catalyzed (Cp*=C5Me5) dehydrogenativecross‐coupling of benzamides with simple benzene derivatives (see scheme, DG=directing group). Similarly, heterocycles can be coupled and druglike structures formed. Mechanistic studies suggest a unique and multiple role of the Cu(OAc)2/C6Br6 system and a nonchelate‐assisted CH activation as the
C 6 Br六和 毒品!C 6 Br 6可用作苯甲酰胺与简单苯衍生物的[Rh III Cp *]催化(Cp * = C 5 Me 5)脱氢交叉偶联的助氧化剂/催化剂改性剂(请参见方案,DG =指导基团)。类似地,杂环可以偶联并形成药物样结构。机理研究表明,Cu(OAc)2 / C 6 Br 6系统具有独特的多重作用,而非螯合物辅助的CH活化是决定速率的步骤。
Dual Effects of Cyclopentadienyl Ligands on Rh(III)-Catalyzed Dehydrogenative Arylation of Electron-Rich Alkenes
ligand not only can facilitate the electrophilic aryl C–H rhodation but also can lower the olefin insertion barrier. Both electron-withdrawing and electron-donating directing groups such as -CONR2 and -NHAc could be employed in these reactions, which provides convenient routes toward a series styryl acetates, N-acetylindoles, and aryl methyl ketones.
尽管对过渡金属催化的Fujiwara–Moritani C–H型烯烃进行了广泛的研究,但这些转化中使用的烯烃仍主要限于活性丙烯酸酯和苯乙烯。富电子烯烃的选择性芳基CH烯化反应被认为是一个具有挑战性的问题。我们在本文中报道,简单且易于接近的缺电子的[CpRh(III)]和[Cp CF 3 Rh(III)](Cp CF 3 = C 5 Me 4 CF 3)配合物是富电子脱氢芳基化的有力催化剂烯烃,包括乙酸乙烯酯,酰胺和乙烯基醚。使用吸电子Cp或Cp CF 3配体代替特权Cp *(C5 Me 5)配体不仅可以促进亲电芳基C–H的铑基化,而且可以降低烯烃的插入势垒。在这些反应中都可以使用吸电子和供电子导向基团,例如-CONR 2和-NHAc,这提供了通向一系列乙酸苯乙烯酯,N-乙酰吲哚和芳基甲基酮的便捷途径。
Benzylic aroylation of toluenes with unactivated tertiary benzamides promoted by directed ortho-lithiation
amides and highly reactive organometallic reagents bring great challenges for an efficient and selective synthetic approach. Herein, we reported an lithium diisopropylamide (LDA)-promoted benzylic aroylation of toluenes with unactivated tertiary benzamides, providing a direct and efficient synthesis of various aryl benzyl ketones. This process features a kinetic deprotonative functionalization of toluenes
We report a uniquely high-yielding, general, and practical ortho bromination and iodination reaction of different classes of aromatic compounds. This reaction occurs by Rh(III)-catalyzed C-H bond activation methodology and is therefore the first example of the application of this cationic catalyst for C-Br and C-I bond formation.