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The structure and spectroscopic properties of the amide bond are a topic of fundamental interest in chemistry and biology. Herein, we report 17 O NMR and 15 N NMR spectroscopic data for four series of sterically-hindered acyclic amides. Despite the utility of 17 O NMR and 15 N NMR spectroscopy, these methods are severely underutilized in the experimental determination of electronic properties of the amide bond. The data demonstrate that a combined use of 17 O NMR and 15 N NMR serves as a powerful tool in assessing electronic effects of the amide bond substitution as a measure of electrophilicity of the amide bond. Notably, we demonstrate that steric destabilization of the amide bond results in electronically-activated amides that are comparable in terms of electrophilicity to acyl fluorides and carboxylic acid anhydrides. 

First update on zinc cyanide for all chemists planning or working on organic syntheses is presented. 

Amides are of fundamental interest in many fields of chemistry involving organic synthesis, chemical biology and biochemistry. Here, we report the first catalytic Buchwald-Hartwig coupling of both common esters and amides by highly selective C(acyl)–X (X = O, N) cleavage to rapidly access aryl amide functionality via crosscoupling strategy. Reactions are promoted by versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts, proceed in good to excellent yields and with excellent chemoselectivity for the acyl bond cleavage. The method is user friendly because it employs commercially-available, moisture- and air-stable precatalysts. Notably, for the first time we demonstrate selective C(acyl)–N and C(acyl)–O cleavage/Buchwald-Hartwig amination under the same reaction conditions, which allows for streamlining amide synthesis by avoiding restriction to a particular acyl metal precursor. Of broad interest, this study opens the door to using a family of well-defined Pd(II)-NHC precatalysts bearing pyridine ͞throw-away ligands for the selective C-acyl–amination of bench-stable carboxylic acid derivatives. 

A Pd-PEPPSI-catalyzed (Pd = Palladium, PEPPSI = pyridine-enhanced precatalyst preparation stabilization and initiation) Suzuki-Miyaura cross-coupling of aryl esters via selective C–O cleavage at room temperature is reported. The developed catalyst system displays broad substrate scope with respect to both components under practical ambient reaction conditions using readily-available, cheap, modular, air- and moisturestable Pd-NHC precatalyst (NHC = N-heterocyclic carbene). The use of water proved crucial for achieving high reactivity in this coupling. The catalyst system represents the mildest conditions for the Suzuki-Miyaura cross-coupling of aryl esters reported to date. The protocol also allowed for achieving TON >1,000 (TON = turnover number) in the Suzuki-Miyaura ester coupling for the first time.