While esters are frequently used as traditional electrophiles in substitution chemistry,t heir application in cross-coupling chemistry is still in its infancy.T his work demonstrates that methyl esters can be used as coupling electrophiles in Ni-catalyzed Heck-type reactions through the challenging cleavage of the C(acyl) À Ob ond under relatively mild reaction conditions at either 80 or 100 8 8C. With the s-Ni II intermediate generated from the insertion of acyl Ni II species into the tethered C=Cb ond, carbonyl-retentive products were formed by domino Heck/Suzuki-Miyaura coupling and Heck/ reduction pathwaysw hen organoboron and mild hydride nucleophiles are used.

Two series of novel 2,4-diphenyl-1,3-oxazolines containing an oxime ether moiety were designed and synthesized via the key intermediate N-(2-chloro-1-(p-tolyl)ethyl)-2,6-difluorobenzamide. The bioassay results showed that the target compounds with an oxime ether substituent at the para position of 4-phenyl exhibited excellent acaricidal activity against Tetranychus cinnabarinus in the laboratory. Moreover, all of the target compounds had much higher activities than etoxazole, as the ovicidal and larvicidal activities of the target compounds I-a-I-l and II-a-II-n against T. cinnabarinus were all over 90% at 0.001 mg L, but etoxazole gave only 30% and 40% respectively at the same concentration. The activity order of compounds with regard to acaricidal activity in vivo was almost consistent with their affinity activity with sulfonylurea receptor (SUR) of Blattella germanica in vitro, hence, it was supposed that the acaricidal mechanism of action of the target compounds was that they can bind with the site of SUR and therefore inhibit chitin synthesis. Moreover, the eminent effect of the compound II-l, [2-(trifluoromethyl)benzaldehyde O-(4-(2-(2,6-difluorophenyl)-4,5-dihydrooxazol-4-yl)benzyl) oxime], against Panonychus citri and T. cinnabarinus in the field indicated that II-l exhibited a promising application prospect as a new candicate for controlling spider mites in the field.

Amide bond formation and transition metalcatalyzed cross-coupling are two of the most frequently used chemical reactions in organic synthesis. Recently, an overlap between these two reaction families was identified when Pd and Ni catalysts were demonstrated to cleave the strong C−O bond present in esters via oxidative addition. When simple methyl and ethyl esters are used, this transformation provides a powerful alternative to classical amide bond formations, which commonly feature stoichiometric activating agents. Thus far, few redox-active catalysts have been demonstrated to activate the C(acyl)−O bond of alkyl esters, which makes it difficult to perform informed screening when a challenging reaction needs optimization. We demonstrate that Ni catalysts bearing diverse NHC, phosphine, and nitrogen-containing ligands can all be used to activate methyl esters and enable their use in direct amide bond formation.

Cross-coupling reactions to form biaryls and  bond addition reactions to prepare substituted carbonyls or alcohols represent two of the most frequently performed families of chemical reactions. Recent progress in...

We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl-derivatives. This is achieved by the action of a Ni/NHC catalyst and an organosilane reducing agent that is activated in situ by stoichiometric KOtBu. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require use of hazardous metal hydrides. Applications in the synthesis of-CD3 containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other CO bonds is demonstrated. File list (2) download file view on ChemRxiv Manuscript.pdf (1.92 MiB) download file view on ChemRxiv Supporting information.pdf (4.97 MiB)