Review Articles in 2022

1,4-Dicarbonyls are challenging targets owing to the natural-polarity mismatch of potential reaction partners. This Review discusses methods for 1,4-dicarbonyl synthesis based on the coupling of two carbonyl-containing fragments as well as methods that involve non-carbonyl precursors. A spotlight on 1,4-dicarbonyls in total synthesis underlines the diversity of approaches for this motif.

Nucleophiles are versatile reagents that can engage in a plethora of C–C and C–heteroatom bond-forming reactions. This Review examines their increasing role in transition metal-catalysed directed C–H functionalization, with a focus on synthetic approaches involving organometallic nucleophiles and X-based (X = N, O and S) coupling partners.

Polar effects permeate radical chemistry and control the outcome of radical reactions. This Review discusses important types of polar effects and how their interplay has been used in the synthesis and late-stage modification of complex molecules. The discussion covers hydrogen-atom transfer, halogen-atom transfer and homolytic aromatic substitution.

MXenes are 2D materials with a rich chemistry and applications in energy storage, electronics and biomedicine. This Review discusses various MXene syntheses—from layered precursors to single-layer 2D flakes—including principles behind these methods and synthesis–structure–property relationships.

Metals in their zero-valent form offer a great deal of potential for chemical synthesis. The reliable and straightforward activation of these raw materials has perhaps inhibited the full realization of this promise. This review examines the emergence of the technique of ball milling as a reactor technology to enable mechanical activation of zero-valent metals.

Crystal engineering of nanosized and hierarchical zeolites may improve the mass transport properties of materials at the nanoscale in various applications. In this Review, synthetic methods used to prepare different classes of zeolitic materials are summarized, with a focus on nucleation and growth mechanisms. Experimental and computational advances, as well as future challenges in the field, are discussed.

Catalytic asymmetric transformations of quinone methides and indole imine methides involve catalysts such as chiral Brønsted acids, Lewis acids and bases as well as transition metal complexes. In this Review, these asymmetric transformations are discussed with a focus on reaction pathways and activation modes.

Alkaline earth elements are among the most abundant and cost-effective metals in the toolbox of synthetic chemists and investigations of their structures and bonding have led to fascinating discoveries. This Review discusses the emerging synthetic chemistry and unusual redox chemistry of low-oxidation-state Be, Mg and Ca complexes.

Molecular editing allows structures to be built up in terms of complexity, or changed or pruned one atom at a time using transformations which are mild and selective enough to be employed at the late stages of a synthetic sequence. In this Review, a subclass of molecular editing reactions termed ‘single-atom skeletal editing’ are described, with a particular focus on heterocycles.

Reductive coupling reactions mediated by samarium(ii) iodide are useful transformations to form C–C bonds. The unique reactivity and selectivity of SmI₂ result in its wide application in key steps in the total synthesis of natural products. This Review outlines synthetic routes using this versatility to make important C–C bonds in complex products.

Cascade dearomative cyclization reactions are an important subclass of catalytic asymmetric dearomatization reactions, for the synthesis of polycyclic scaffolds. In this Review, cascade asymmetric dearomative cyclization reactions which are catalysed by transition-metal complexes are discussed, with a focus on the cyclization of indoles and related heteroaromatic compounds.

Inorganic nanocrystals coated with surfactant-like organic molecules have a vast range of properties arising from the combination of their components. In this Review, the role of the organic ligands on the synthesis of colloidal nanocrystals is discussed with a focus on the tails of the ligands and their collective effects on the surface.

Boronic esters are versatile intermediates that readily accept nucleophiles and then undergo 1,2-migration, expelling a neighbouring leaving group. Such reactivity enables carbon chains to be grown one atom at a time with high stereocontrol. This Review examines the fundamentals of lithiation–borylation methodology and its application to natural product synthesis.

Remote functionalization through alkene isomerization is a popular strategy in organic synthesis. The dynamic nature of alkene isomerization typically leads to difficulties in controlling the stereochemistry of C(sp³) centres along the carbon skeleton. This Review outlines synthetic methods that tackle this issue and leverage alkene isomerization to control C(sp³) stereocentres in complex organic molecules.

Oximes are valuable motifs with diverse reactivity. This Review outlines the breadth of oxime reactivity including N–O bond fragmentation through transition metal catalysis and photocatalysis, [2 + 2]-cycloaddition reactions, asymmetric reduction and applications in materials science. Developments in transition metal catalysis and photocatalysis highlight the use of oximes as powerful synthetic building blocks.