Amide‐Directed Tandem C?C/C?N Bond Formation through C?H Activation

The transformation of C? H bonds into other chemical bonds is of great significance in synthetic chemistry. C? H bond‐activation processes provide a straightforward and atom‐economic strategy for the construction of complex structures; as such, they have attracted widespread interest over the past decade. As a prevalent directing group in the field of C? H activation, the amide group not only offers excellent regiodirecting ability, but is also a potential C? N bond precursor. As a consequence, a variety of nitrogen‐containing heterocycles have been obtained by using these reactions. This Focus Review addresses the recent research into the amide‐directed tandem C? C/C? N bond‐formation process through C? H activation. The large body of research in this field over the past three years has established it as one of the most‐important topics in organic chemistry.     

Deprotonation of C‐Alkyl Groups of Cationic Triruthenium Clusters Containing Cyclometalated C‐Alkylpyrazinium Ligands: Experimental and Computational Studies

The C‐alkyl groups of cationic triruthenium cluster complexes of the type [Ru₃(μ‐H)(μ‐κ²N¹,C² ‐L)(CO)₁₀]⁺ (HL represents a generic C‐alkyl‐N‐methylpyrazium species) have been deprotonated to give kinetic products that contain unprecedented C‐alkylidene derivatives and maintain the original edge‐bridged decacarbonyl structure. When the starting complexes contain various C‐alkyl groups, the selectivity of these deprotonation reactions is related to the atomic charges of the alkyl H atoms, as suggested by DFT/natural‐bond orbital (NBO) calculations. Three additional electronic properties of the C‐alkyl C? H bonds have also been found to correlate with the experimental regioselectivity because, in all cases, the deprotonated C? H bond has the smallest electron density at the bond critical point, the greatest Laplacian of the electron density at the bond critical point, and the greatest total energy density ratio at the bond critical point (computed by using the quantum theory of atoms in molecules, QTAIM). The kinetic decacarbonyl products evolve, under appropriate reaction conditions that depend upon the position of the C‐alkylidene group in the heterocyclic ring, toward face‐capped nonacarbonyl derivatives (thermodynamic products). The position of the C‐alkylidene group in the heterocyclic ring determines the distribution of single and double bonds within the ligand ring, which strongly affects the stability of the neutral decacarbonyl complexes and the way these ligands coordinate to the metal atoms in the nonacarbonyl products. The mechanisms of these decacarbonylation processes have been investigated by DFT methods, which have rationalized the structures observed for the final products and have shed light on the different kinetic and thermodynamic stabilities of the reaction intermediates, thus explaining the reaction conditions experimentally required by each transformation.     

CN and CC Bond Formations in the Thermal Reactions of "Bare" Ni(NH(2) )(+) with C(2) H(4) : Mechanistic Insight on the Metal-Mediated Hydroamination of an Unactivated Olefin

Strike! While pure ammonia is out of luck, Ni(NH(2) )(+) gets one strike after another at the "ethylene bowling championship". In fact, Ni(NH(2) )(+) is so effective that no pin, not even at the neighboring lane, is safe from it.