Targeting distal C–H bonds in arenes: The Friedel-Crafts reaction is among the oldest in organic chemistry. For well over a century, chemists have relied on electronic effects intrinsic to aryl rings to append substituents at specific sites along the periphery. However, only in the past decade have they devised catalytic techniques that over-ride these preferences so that new groups usually drawn to the neighboring sites of an existing substituent instead wind up two or three carbons away. Dutta et al. review progress in this field, highlighting elaborate directing groups and mediators as well as sophisticated ligand design. Science , this issue p. eabd5992

In industries and academic laboratories, several late transition metal-catalyzed prerequisite reactions are widely performed during single and multistep synthesis. However, besides the desired products, these reactions lead to the generation of numerous chemical waste materials, by-products, hazardous gases, and other poisonous materials, which are discarded in the environment. This is partly responsible for the creation of global warming, resulting in climate adversities. Thus, the development of environmentally benign, cheap, easily accessible, and earth-abundant metal catalysts is desirable to minimize these issues. Certainly, iron is one of the most important metals belonging to this family. The field of iron catalysis has been explored in the last two-three decades out of its rich chemistry depending on its oxidation states and ligand cooperation. Moreover, this field has been enriched by the promising development of iron-catalyzed reactions namely, C–H bond activation, including organometallic C–H activation and C–H functionalization via outer-sphere pathway, cross-dehydrogenative couplings, insertion reactions, cross-coupling reactions, hydrogenations including hydrogen borrowing reactions, hydrosilylation and hydroboration, addition reactions and substitution reactions. Thus, herein an inclusive overview of these reaction have been well documented.

This review summarises deuteration methods of various organic motifs containing C(sp ² )−H and C(sp ³ )−H bonds utilizing C−H bond functionalisation as a key step along with a variety of catalysts, and exemplifies their biological relevance.