Articles in 2020

Although methods exist for the construction of CF₃-containing stereocentres, the utilization of α-trifluoromethyl carbanions remains challenging because of the propensity for fluoride elimination. A strategy has now been developed to stabilize these carbanions through a neighbouring cationic Pd complex and the corresponding Pd-stabilized zwitterions participate in asymmetric cycloadditions with a broad range of acceptors.

The structures of biologically active natural products have long served as inspiration in drug discovery. This Perspective outlines design principles and connectivity patterns for the de novo combination of natural product-derived fragments. The resulting ‘pseudo-natural products’ retain biological relevance yet exhibit structures and bioactivities not found in the natural products and their derivatives.

It is crucial to replace fossil fuel-based plastics with biodegradable ones that are made from renewable sources. Now, a new generation of bioplastics has been prepared through the stereoselective polymerization of diastereomeric monomers — a synthetic approach that allows tuning of the materials’ toughness, ductility and melting point.

Bruce C. Gibb takes a look at the dark side of academia and considers a multitude of sins.

Monoclonal antibodies have shown tremendous success in cancer treatment; however, humanization for clinical applications is expensive and not straightforward. Now, molecularly imprinted polymer nanogels have been developed that can block cell-surface proteins and disrupt tumour spheroids.

Synthetic organic chemistry is increasingly automated, data rich and intelligent. At the Automated Synthesis Forum, industry and academia showcased their recent progress towards this augmented future.

Academic labs can be difficult places to work — but why is that the case and what can be done to address the issues that lead to harmful working environments?

Growing polymers directly on surfaces has emerged as a powerful tool because it can provide a route to otherwise inaccessible structures such as defect-free linear chains, graphene nanoribbons and two-dimensional networks. This Review Article describes general principles and key aspects of this method from the perspectives of surface science and polymer chemistry.

Meroterpenoids are mixed terpenoid–polyketide natural products with a variety of biological activities. Now, a synthetic approach that combines biocatalytic oxidation with a range of other radical-based reactions enables the divergent synthesis of eight oxidized meroterpenoid natural products and one analogue.

Does aromaticity have a size limit? Evidence is presented for global aromaticity in porphyrin nanorings with circuits of up to 162 π-electrons. The conformation of the nanoring can be altered by changing the template, which in turn controls the aromaticity. Whenever a ring current is observed, its direction is correctly predicted by Hückel’s rule.

Homogeneous photocatalysts for the conversion and storage of solar energy typically feature separate sensitizer–catalyst assemblies, whereas previous examples of single-chromophore single-molecule photocatalysts are inefficient and do not use significant portions of the visible spectrum. Now a dirhodium single-chromophore single-molecule catalyst has been developed that generates hydrogen using low-energy light through a previously unobserved mechanism.

The Varkud satellite ribozyme, which catalyses site-specific RNA cleavage and ligation, is an important model to understand RNA catalysis. Now, a combination of theoretical and experimental work has revealed new details about its catalytic mechanism. Mg²⁺ is shown to play an important role in organizing the active site, and the proton transfers in the transition state have also been identified.

Homooligomerization systems can be used to construct nanoarchitectures and to aid understanding of natural analogues. But the formation of such artificial systems with structural diversity and complexity comparable to that of biological systems is challenging. Now, an artificial branched kissing-loop motif has been designed, which links tiles folded from a single strand of RNA to give diverse homooligomeric nanostructures.

A conjugated diradicaloid cage has been synthesized and its aromaticity was investigated. The neutral compound and the dication have dominant monocyclic conjugation pathways and both are aromatic (the former following Hückel’s rule and the latter Baird’s rule). The tetracation ([6n + 4] π-electrons) exhibits global 3D antiaromaticity whereas the hexacation ([6n + 2] π-electrons) exhibits global 3D aromaticity and has high D₃ symmetry.

Meroterpenoids are mixed terpenoid–polyketide natural products that exhibit a range of biological activities. A hybrid synthetic strategy that combines biocatalytic and radical-based methods has now been developed and it enables eight different oxidized meroterpenoids to be made in just 7–12 steps from commercially available materials.

Carbon capture technologies are poised to play an important role in reducing CO₂ emissions to mitigate global warming, but their cost prevents their extensive use. Now, CO₂ capture and utilization have been combined using a triple-level dynamic combinatorial approach. CO₂ was spontaneously captured by industrial polyamines to create libraries of ligands that can be used for the separation and recovery of metals.

The mechanochemical activation of [4]-ladderane/ene has been studied and found to exhibit cascade unzipping and a consistent stereochemical distribution of products under various conditions and in different polymer backbones. Ab initio steered molecular dynamics simulations revealed unique non-equilibrium dynamic effects in the mechanochemistry of ladderane, cascade activation and reaction pathway bifurcation.