The ligand [2, 2'-bipyridin]-6(1H)-one (bipy-6-OH) has a strong accelerating effect in the Pd-catalyzed direct arylation of pyridine or arenes. The isolation of relevant intermediates and the study of their decomposition unequivocally show that the deprotonated coordinated ligand acts as a base and assists the cleavage of the C-H bond. Mechanistic work indicates that the direct arylation of pyridine with this ligand occurs through a Pd(0)/Pd(II) cycle. Because of this dual ligand-intramolecular base role, there is no need of an available coordination site on the metal for an external base, a difficulty encountered when chelating ligands are used in coupling reactions that involve a C-H cleavage step.

Fluoroarenes can be selectively deuterated by H/D exchange with common deuterated solvents in the presence of a catalytic amount of an alkali metal carbonate or, for the less acidic arenes, stoichiometric quantities of potassium phosphate. This is a sustainable method that does not need transition metal catalysis or the multistep synthesis of a main‐group organometallics. This exchange needs to be taken into account when using H/D scrambling as a mechanistic probe in reactions involving fluoroarenes.

The functionalization of simple arenes without coordinating directing groups is a challenge. Besides facing the task of cleaving the sluggish C-H bond, the process is hampered by the weak coordinating...

Metal-catalyzed C−H functionalizations on the aryl ring of anilines usually need cumbersome N-protection−deprotection strategies to ensure chemoselectivity. We describe here the Pd-catalyzed direct C−H arylation of unprotected anilines with no competition of the N-arylation product. The ligand [2,2′-bipyridin]-6(1H)-one drives the chemoselectivity by kinetic differentiation in the product-forming step, while playing a cooperating role in the C−H cleavage step. The latter is favored in an anionic intermediate where the NH moiety is deprotonated, driving the regioselectivity of the reaction toward ortho substitution.

The transmetalation of acyclic monoamino and alkoxo carbenes from tungsten to group 11 metals has been studied for all three metals by analyzing the new metal carbenes formed and also their decomposition products in solution. The ease of transmetalation follows the trend: Au > Cu > Ag and the gold carbenes can be isolated, a copper carbene could be detected but we found no experimental evidence of the formation of any silver carbene. The electrophilic character of copper and gold carbenes is supported by the identity of the products formed upon hydrolysis of the carbenes involved. Silver shows a distinct behavior and the presence of Ag + ions in an acetonitrile solution of a tungsten aminocarbene leads to the formal protonation of the carbene fragment to give an iminium salt. This outcome, a seemingly nucleophillic behavior, is unexpected for group 11 carbenes but DFT calculations show that the protonation of a putative cationic silver carbene is energetically accessible.

Mechanistic proposals for the C-H activation reaction enabled by mono-N-protected amino acid ligands (MPAAs) have been supported by DFT calculations. The direct experimental observation of the ligand-assisted C-H activation has...

The Cover Feature shows the selective and convenient deuteration of fluoroarenes carried out using a common deuterated solvent, such as [D6]‐acetone, [D6]‐DMSO or D2O, in the presence of carbonate or phosphate. A player represents this combination of base and solvent that touches the fluoroarene and effectively kicks off the deuteration process. This method has left other players in the field, that have had a role in this transformation for very specific cases, on the bench. Main‐group elements, used for this purpose via the synthesis or organometallic derivatives and subsequent hydrolysis, are represented in the dugout, as well as transition metals that have been used as catalysts for few of the cases. More information can be found in the Full Paper by V. Salamanca and A. C. Albéniz.