Copper-Catalyzed Cross-Coupling of Functionalized Alkyl Halides and Tosylates with Secondary and Tertiary Alkyl Grignard Reagents

Quaternary Centers by Nickel-Catalyzed Cross-Coupling of Tertiary Carboxylic Acids and (Hetero)Aryl Zinc Reagents

This work bridges a gap in the cross-coupling of aliphatic redox-active esters with aryl zinc reagents. Previously limited to primary, secondary, and specialized tertiary centers, a new protocol has been devised to enable the coupling of general tertiary systems using nickel catalysis. The scope of this operationally simple method is broad, and it can be used to simplify the synthesis of medicinally relevant motifs bearing quaternary centers.

Catalyst-Controlled 1,2- and 1,1-Arylboration of α-Alkyl Alkenyl Arenes

Two methods are reported for the 1,2- and 1,1-arylboration of α-methyl vinyl arenes. In the case of 1,2-arylboration, the formation of a quaternary center occurred through a rare cross-coupling reaction of a tertiary organometallic complex. 1,1-Arylboration was enabled by catalyst optimization and occurred through a β-hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations.

Gold(I)-catalyzed Benzylation of (Hetero)aryl Boronic Acids with (Hetero)benzyl Bromides by the Strategy of a SN 2-type Reaction

Herein, the first example of gold-catalyzed benzylation of (hetero)aryl boronic acids with (hetero)benzyl bromides to give the corresponding cross-coupling products in moderate to good yields is reported. The reaction proceeds through a possible intermolecular S_N 2-type reaction pathway to give a wide variety of di(hetero)arylmethanes as the desired products. An intriguing reaction mechanism has been proposed on the basis of control experiments, ³¹ P-NMR spectroscopic detection and DFT calculations.

Ligand-Controlled Regiodivergent Copper-Catalyzed Alkylboration of Alkenes

A novel copper-catalyzed regiodivergent alkylboration of alkenes with bis(pinacolato)diboron and alkyl halides has been developed. The regioselectivity of the alkylboration was controlled by subtle differences in the ligand structure. The reaction thus enables the practical, regiodivergent synthesis of two different alkyl boronic esters with complex structures from a single alkene.

Is TiO2 (B) the Future of Titanium-Based Battery Materials?

Titania materials are gaining interest as negative electrode materials in Li-ion batteries due to their high power capability and enhanced safety. Today, Li₄ Ti₅ O₁₂ is the material of choice for commercial batteries, but other titania materials, namely polymorphs of TiO₂ , are being explored because of their similar electrochemical behavior and higher theoretical specific charge capacity. In practice, the specific charge capacity of TiO₂ remains far below the theoretical value of 336 mA h g^-1 due to poor electrical conductivity and slow Li-ion mobility. This Minireview describes the main strategies developed to overcome the limitations of TiO₂ polymorphs. Special attention is given to TiO₂ (B) since its outstanding Li-ion mobility, the highest mobility among all TiO₂ polymorphs, has led to superior electrochemical performance. Finally, the potential of titania materials in sodium-ion batteries is also discussed.