Volume 1 Issue 5, May 2022

The predictable transition-metal-catalysed cyclotrimerization of three different unsaturated substrates in a controlled selective manner is a challenge for synthetic chemists. Now, a highly selective chiral rhodium-catalysed reaction provides selective access to a range of six-membered carbocyclic rings.

Aryl ethers are privileged scaffolds in contemporary drug-discovery programs. Now, employment of triplet states of aryl halides enables copper-mediated cross-coupling with various alcohols for the expedient synthesis of aryl ethers.

Heterogeneous catalysis is often plagued by incompatibility of a catalyst’s reactivity and stability. Now, covalent organic frameworks linked by reactive, yet stable, N-heterocyclic carbene precursors are synthesized and the frameworks are subsequently used as cathodes in Li–S batteries.

Despite 40 years of study, the synthesis of colloidal nanocrystals still proceeds by a trial and error approach. This Perspective discusses the identification of the reaction intermediates during the formation of colloidal nanocrystals as the first step towards the development of a retrosynthetic approach to these nanomaterials.

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.

The [2+2+2] cyclotrimerization of two distinct alkynes and alkenes to form six-membered carbocycles is typically constrained by competing β-hydride elimination, low stereocontrol and the need to add reagents slowly. Now, a rhodium-catalysed three-component [2+2+2] cyclotrimerization with excellent chemo-, regio- and stereocontrol is reported that does not require any special operations. The utility of the process is shown and mechanistic studies probe the origins of the selectivity.

Cross-coupling reactions between aryl halides and alcohols using copper are challenging due to the energetically demanding oxidative addition of copper into aryl halides. Now, this high-barrier step is bypassed using an energy transfer or direct excitation strategy for copper-mediated cross-coupling reactions. This process enables the use of aryl chlorides as electrophiles and alcohols, amines and fluoride as nucleophilic coupling partners.

Making highly crystalline covalent organic frameworks (COFs) is challenging and existing linkages used for constructing COFs are limited in terms of variety and functionality. Now, crystalline COFs with imidazopyridinium linkages, which serve as precursors to N-heterocyclic carbenes, have been synthesized, expanding the reactivity of COFs by incorporating chemical ambivalence (electrophilicity and nucleophilicity) into the linkages. The COFs are also used as cathode materials in lithium–sulfur batteries.

Making many stereogenic centres in a single step remains a challenge. Now, a combined nickel and copper-catalysed stereodivergent propargylic substitution process has been developed to access four stereoisomers of amathaspiramide D. The scope of the reaction is shown across a range of propargylic carbonate and aldimine ester substrates to generate a number of chiral propargylated α-amino ester products.

Enantioselective dearomatization of substituted non-activated benzene derivatives is a challenge due to their inherent stability. Now, a chiral samarium complex-mediated enantioselective dearomatization of substituted benzene derivatives is realized via intramolecular reductive coupling with ketyl radicals. The method has been used to synthesize a range of dearomatized bicycles with three stereogenic centres.