Pd(II)-catalysed meta-C–H functionalizations of benzoic acid derivatives

Abstract

Benzoic acids are highly important structural motifs in drug molecules and natural products. Selective C–H bond functionalization of benzoic acids will provide synthetically useful tools for step-economical organic synthesis. Although direct ortho-C–H functionalizations of benzoic acids or their derivatives have been intensely studied, the ability to activate meta-C–H bond of benzoic acids or their derivatives in a general manner via transition-metal catalysis has been largely unsuccessful. Although chelation-assisted meta-C–H functionalization of electron-rich arenes was reported, chelation-assisted meta-C–H activation of electron-poor arenes such as benzoic acid derivatives remains a formidable challenge. Herein, we report a general protocol for meta-C–H olefination of benzoic acid derivatives using a nitrile-based sulfonamide template. A broad range of benzoic acid derivatives are meta-selectively olefinated using molecular oxygen as the terminal oxidant. The meta-C–H acetoxylation, product of which is further transformed at the meta-position, is also reported.

Accessing Remote meta‐ and para‐C(sp2)−H Bonds with Covalently Attached Directing Groups

“…[20] Whereas the nitrile group still served as aw eak coordinator to the palladium precatalyst, an N-nosyl-substituted phenethyl-based director was found to yield ag ood range of meta-olefinated and metaacetoxylated products (Scheme 8). [20] Whereas the nitrile group still served as aw eak coordinator to the palladium precatalyst, an N-nosyl-substituted phenethyl-based director was found to yield ag ood range of meta-olefinated and metaacetoxylated products (Scheme 8).…”

“…carbonyl hydrocinnammic acid meta-olefination (R = H) meta-arylation (R = OMe) [9] [11] phenols meta-olefination (R = H) meta-arylation (R = H) [11] phenylacetic acid meta-olefination (R = H) [18] tetrahydroquinoline meta-olefination [15] aniline meta-olefination meta-acetoxylation [15] phenylacetic acid meta-olefination [17] phenylethylamine meta-olefination [19] benzoic acid meta-olefination meta-acetoxylation [20] …”

Competition between the inter-valley scattering and the intra-valley scattering on magnetoconductivity induced by screened Coulomb disorder in Weyl semimetals

“…From recent experiments on Weyl semimetals, we observe several key facts. 1) The chemical potential is sample-dependent 45 ; 2) The carrier density can be varied in several orders and the mobility can be different in one order 32,34,45,46 ; 3) The longitudinal negative MR (related to σ zz ) corresponding to the chiral anomaly may not be observed in every experiment 45 . From the first and second facts, we may conclude that there exist charged impurities in realistic samples and the density of the impurity is sample-dependent.…”

Zugang zu meta‐ und para‐C(sp2)‐H‐Bindungen mithilfe kovalent gebundener dirigierender Gruppen

“…Anschließend berichtete die gleiche Arbeitsgruppe über eine leistungsfähige meta ‐selektive Funktionalisierung von Benzoesäure durch ein Amid‐verbrücktes Templat (Schema ) . Während die Nitrilgruppe weiterhin als schwach koordinierende Gruppe im Palladium‐Präkatalysator diente, wurde ein N ‐Nosyl‐substituierter phenethylbasierter Linker gefunden, der eine gute Auswahl an meta ‐olefinierten und meta ‐acetoxylierten Produkten hervorbrachte (Schema ).…”