Palladium‐Catalyzed Synthesis of Aromatic Ketones and Isoindolobenzimidazoles via Selective Aromatic CH Bond Acylation

Abstract

A convenient and efficient palladium-catalyzed synthesis of aromatic ketones and isoindolobenzimidazoles has been developed via selective aromatic C À H bond acylation. The protocol uses palladium acetate as the catalyst, readily available carboxylic acids as the acylating reagents, trifluoroacetic anhydride as the activated agent of the acids, and the corresponding aromatic ketones and isoindolobenzi-midazoles were obtained in good to excellent yields. This finding should provide a new and useful strategy for synthesis of aromatic ketones and isoindolobenzimidazoles.Scheme 4. Possible mechanism for the palladium-catalyzed synthesis of isoindolobenzimidazoles.

Palladium‐Catalyzed C2‐Acylation of Indoles with α‐Diketones Assisted by the Removable N‐(2‐Pyrimidyl) Group

“…In past decades, innovative methods have been developed to synthesize 2-acylindoles under various catalytic conditions. [17] Such ortho-acylation reactions were also realized by using alcohols, [18] carboxylic acids, [19] benzylic ethers, [20] benzylamines, [21] α-diketones, [22] α-oxocarboxylic acids, [23] or toluene derivatives [24] as acylation reagents. [13] Li and co-workers demonstrated oxidative C2 acylation of indoles by using an expensive rhodium catalyst.…”

Acylation of (Hetero)Arenes through CH Activation with Aroyl Surrogates

“…In the same period, Fu and co‐workers reported a palladium‐catalyzed version of this transformation 69. By the in situ generation of mixed acid anhydride from acid and trifluoroacetic anhydride (TFAA), 2‐arylpyridines were acylated in the presence of palladium acetate, giving the desired ketones in good yields (Scheme ).…”

Palladium-Catalyzed Direct Ortho Aroylation of 2-Phenoxypyridines with Aldehydes and Catalytic Mechanism Investigation

“…1,2 Among these methods, the direct and selective ortho aroylation of arenes has been frequently studied by the employment of various aroyl sources, such as aldehydes, 3 alcohols, 4 α-keto acids, 5 toluenes, 6 diketones, 7 carboxylic acids, 8 benzylamines, 9 and benzylic ethers. 10 On the basis of these developed strategies, a variety of aryl ketones can be readily prepared via direct C−H functionalization.…”