The isolation of secondary and primary carbon radical species is challenging, owing to their instability. Now the reduction of an acyclic bis(imino)carbene conjugate acid enables the isolation of a stable pentadienyl-type radical. In silico and in vitro probing of its properties reveal a propensity to act as a secondary carbon radical.

Acid-triggered reversible addition–fragmentation chain-transfer polymerizations, in the absence of conventional initiating species and in the dark, are reported to prepare polymers with low dispersity and high end-group fidelity. The protonation of monomers catalyses both the initiation and propagation steps and can also be applied to free radical polymerizations.

The synthesis of high-nuclearity copper(I) nanoclusters remains challenging due to their low stability. Now four high-nuclearity Cu(I) nanoclusters have been successfully isolated by introducing a bifunctional phosphoramide ligand into the Cu/RC≡CH assembly system, enhancing complex stability through cooperative bonding.

Enzymatic C–Se bond forming reactions are rare. Now an enzymatic method for the synthesis of organoselenium compounds is reported using an ‘element engineering’ strategy. This method allows selenium analogues of cysteine, thiamine and a chuangxinmycin derivative to be produced using sulfur carrier proteins.

Artificial metalloenzymes are useful catalysts in synthesis, but their use in cells is a challenge. Now, the development of an engineered whole-cell enzymatic cascade, which converts glucose-derived fatty diacids into cycloalkenes, is reported. The cascade process combines a decarboxylase with an artificial metalloenzyme that catalyses an abiotic olefin metathesis reaction.

C-terminal peptide salicylaldehyde ester synthesis is a challenge due to intrinsic epimerization. Now the development of epimerization-free synthesis of peptide C-terminal salicylaldehyde esters is reported. The approach uses side-chain-protected peptides, formed through solid-phase synthesis, and 2-(dichloromethyl)phenol as substrates and proceeds through an O-to-O acyl transfer process.

A library of clusters based on anisotropic polyoxometalate clusters is synthesized. Different phases of superstructures are prepared by tuning interactions between and inside the polyoxometalate building blocks, which adds to our understanding of structure–property relationships at sub-nanometre scale.

Selective electrochemical CO₂ reduction (CO₂RR) in strong acids remains challenging due to competition with the hydrogen evolution reaction. Now it is reported that peripheral functionalization of immobilized molecular complexes with quaternary ammonium groups can regulate the mass distribution surrounding the active sites, enabling selective CO₂RR in strong acids.

The synthesis of α,β-stereogenic tertiary alcohols featuring multiple contiguous stereocentres is a challenge. Now, a method for the enantioconvergent copper-catalysed allylation, propargylation and crotylation of racemic ketones is reported. The process provides access to chiral tertiary alcohols bearing multiple contiguous stereocentres.

The asymmetric total synthesis of alchivemycin A is reported. The synthesis uses a chemoenzymatic approach that comprises de novo skeleton construction and a late-stage enzymatic oxidation cascade.

Marta Costa Figueiredo, an Assistant Professor of electrochemistry at Eindhoven University of Technology, talks to Nature Synthesis about electrocatalysis and the electrochemical formation of C–N bonds.

The electrochemical coupling of waste gaseous carbon and heteroatoms is a potentially sustainable route to value-added chemicals, writes Jennifer Dunn.

Implementing a chemical C–N coupling step to intercept reactive intermediates in electrocatalytic CO₂ or NO_x^y– reduction reactions is an emerging approach to sustainable electrosynthesis of organonitrogen compounds from cheap and abundant feedstocks.

The electrochemical construction of C–N bonds from abundant CO₂ and nitrogenous sources is of interest for the sustainable synthesis of value-added organonitrogen compounds, which requires comprehensive considerations of electrocatalysts, the interface microenvironment, mechanisms, reactors and paired reactions to push this area towards competition with traditional thermochemical methods.