Articles in 2023

Cysteine bioconjugation is an important method to modify biomolecules, but synthetic efforts to diversify reactive warheads and the low reactivity of introducible linchpins often impede application in biological laboratories. Now, a thianthrenium-based reagent permits site-selective installation of episulfonium on biomacromolecules, enabling one-step addition of bioorthogonal nucleophiles and further applications in quantitative proteomics and cross-linking.

In contrast to photothermal therapy requiring high powers over extended times and photodynamic therapy being abrogated by inhibitors of reactive oxygen species, actuation of vibronic modes in single molecules—molecular jackhammers—can now induce efficient cancer cell death. Here, the mechanical disassembly of cell membranes is characterized as the underlying mechanism by which this vibronic-driven action promotes necrotic cell death.

Current proteolysis-targeting chimeras can promote the ubiquitination and subsequent degradation of both target and off-target proteins by inducing their respective proximity with the cereblon ubiquitin ligase. Now, by developing and deploying an off-target profiling platform, ‘bumped proteolysis-targeting chimeras’ can maintain on-target degradation efficacy with reduced off-targets.

Orthogonal click reactions enable the rapid assembly of molecules of all sizes. Now, it has been shown that a nitrile, an allene, a diborane and a hydrazine or aniline can be catalytically merged in a click process that is orthogonal to SuFEx and CuAAC, delivering fluorescent linkages.

Current electrochemical-based protein labelling methods suffer from limited site-selectivity and off-target reactivity owing to required radical/electrophilic reagents. Now an electrochemical strategy enables chemoselective labelling of proteins at a site-specifically incorporated 5-hydroxytryptophan residue using aromatic amines as coupling partners. This approach works on various proteins, including a full-length antibody, and is compatible with established click reactions.

Robust protocols for the synthesis of chiral α-tertiary amino acids remain scarce due to the challenge of constructing congested tetrasubstituted stereocentres. Now a cobalt-catalysed enantioselective aza-Barbier reaction of ketimines with various unactivated alkyl halides has been developed, forming diverse chiral α-tertiary amino esters with high enantioselectivity and excellent functional group tolerance.

The umpolung functionalization of imines bears vast synthetic potential, but polarity inversion is less efficient compared with the carbonyl counterparts. Now, an alternative strategy exploiting chiral phosphoric acid catalytic aromatization has been developed, affording structures possessing a central chirality or a stereogenic C–N axis with high efficiency and enantiocontrol.

Methods for transition-metal-catalysed enantioselective C(sp³)–S bond construction are underdeveloped. Now, by taking advantage of the biomimetic radical homolytic substitution manifold, the copper-catalysed enantioconvergent C(sp³)–S cross-coupling of racemic secondary and tertiary alkyl halides with highly transformable sulfur nucleophiles has been realized. This reaction provides access to an array of α-chiral alkyl organosulfur compounds.

Borenium ions have traditionally served as main group (pre-)catalysts, and their use in materials-related applications have been limited by their instability. Now, a series of fully π-conjugated azaboraacenium ions derived from carbodicarbene have been developed that exhibit high air and moisture stability with full colour-tunable luminescence. Furthermore, these azaboraacene cations mimic the electronic structures of higher-order carbonaceous acenes while featuring enhanced resistance to photo-oxidation.

Light-induced azobenzene cis/trans isomerization has been extensively investigated, but the mechanical strength of its cis/trans structure is not well understood. Now it has been shown that cis azobenzene is mechanically less stable than the trans isomer due to its regiochemical structure, as revealed by single-molecule force spectroscopy.

Activation of H₂ by a metal–olefin complex is characterized experimentally and computationally using a nickel pincer complex, showing that the reaction proceeds via a direct ligand-to-ligand hydrogen transfer mechanism. An application of this cooperative H₂-activation mechanism is demonstrated in the nickel-catalysed semihydrogenation of diphenylacetylene.

Enzyme-initiated polymerization-induced self-assembly has been used to generate various biomimetic structures. Now, myoglobin’s activity is used for biocatalytic polymerization-induced self-assembly to generate vesicular artificial cells. As various cargoes can be encapsulated during polymerization, these artificial cells are capable of protein expression and can act as microreactors for distinct enzymatic reactions.

Many natural products are produced by non-ribosomal peptide synthetases in an assembly-line fashion. How these molecular machines orchestrate the biochemical sequences has remained elusive. It is now understood that an extended-conformation ensemble is needed to coordinate chemical-transformation steps whereas the biosynthesis directionality is driven by the enzyme’s innate conformational free energies.

The synthesis of two-dimensional (2D) organic lateral heterostructures with desirable properties from organic single crystals remains challenging. Now, 2D organic lateral heterostructures have been produced by using a liquid-phase growth approach and vapour-phase growth method, enabling the structural inversion of organic lateral heterostructures via a two-step strategy.

Polymethine dyes are bright and red-shifted fluorophores that lack an intrinsic turn-on mechanism, which leads to non-specific staining when applied to biological samples. Now the fluorescence of polymethine dyes was masked through an intracellular cyclization strategy that gets reversed upon binding an intended macromolecular target, providing specificity for live-cell imaging.

Late-stage functionalization of complex drug molecules is challenging. To address this problem, a discovery platform based on geometric deep learning and high-throughput experimentation was developed. The computational model predicts binary reaction outcome, reaction yield and regioselectivity with low error margins, enabling the functionalization of complex molecules without de novo synthesis.

Long polyynes have fascinating properties but they are difficult to synthesize as a consequence of their high reactivity. Now, it has been shown that cobalt carbonyl complexes can be used as masked alkyne equivalents, enabling the preparation of stable polyyne polyrotaxanes with up to 34 contiguous triple bonds.

The inherent rigidity of the azaarene ring structure has made it challenging to achieve remote stereocontrol through asymmetric catalysis on these substrates. Now, through a photoenzymatic process, an ene-reductase system facilitates the production of diverse azaarenes with distant γ-stereocentres, highlighting the potential of biocatalysts for stereoselectivity at remote sites.

Asymmetric decarboxylation can transform abundant carboxylic acids into valuable chiral molecules but faces major limitations due to the challenging enantiocontrol of proton transfer. Now the use of Brønsted acid catalysis in conjunction with an anchoring group strategy has enabled the decarboxylative protonation of aminomalonic acids to access diverse amino acids.

Alkene hydrofluoroalkylation offers a promising route to diverse fluoroalkylated compounds but current methods have limitations, such as needing expensive fluoroalkylating reagents. Now, leveraging iron photocatalysis and hydrogen-atom-transfer catalysis, a hydrofluoroalkylation method has been developed that utilizes feedstock chemicals such as trifluoroacetic acid as direct fluoroalkyl radical precursors, providing a redox-neutral, general protocol to introduce fluoroalkyl moieties.