Articles in 2022

Principles of quantum interference can guide the design of chromophores that undergo singlet fission. Now, ‘pencil and paper’ graphical models can be used to understand and predict the dynamics of triplet pairs generated through singlet fission in bridged dimers.

Asymmetric systems for catalytic carbohydrate functionalization are mostly limited to chiral copper complexes and organocatalysts. Now, a synergistic chiral Rh(I)- and organoboron-catalysed site-selective functionalization of carbohydrate polyols has been developed, giving stereocontrolled access to biologically relevant arylhydronaphthalene glycosides. Enantio-, diastereo-, regio- and anomeric control and dynamic kinetic resolution were found to be concomitantly operative.

Heteroatom–heteroatom cross-couplings have so far remained elusive. Now, a copper-catalysed enantioselective S–O cross-coupling of diverse diols or triols with sulfonyl chlorides has been realized via a single-electron reductive elimination manifold. The reaction provides access to value-added chiral C₃ building blocks and inositol phosphates through enantioselective desymmetrization of biomass-derived alcohols.

An organic quantum magnet has been prepared in short chains of porphyrin derivatives through a combination of on-surface synthesis and atom manipulation using the tip of a scanning probe microscope.

Macrocyclic peptides can be genetically encoded and synthesized in cells; however, the programmable diversity is limited. Now, macrocycles containing two non-canonical amino acids have been genetically encoded and synthesized in codon-reassigned Syn61Δ3 cells. Incorporating diverse hydroxy acids in Syn61Δ3 cells enables the synthesis of non-natural depsipeptides containing either one or two ester bonds.

The enantioselective functionalization of C₆₀ is highly challenging, typically requiring complex chiral tethers or demanding chromatography. Fullerenes have now been shown to undergo Diels–Alder reactions in a chemo-, regio- and enantio-selective fashion through confinement within an enantiopure metal–organic cage functionalized with a chiral formylpyridine group.

Aromaticity is a ubiquitous concept in organic chemistry yet it is less widespread for inorganic species. Now the cluster [(CpRu)₃Bi₆]^–, obtained as part of a soluble salt, has been shown to exhibit aromatic behaviour referred to as φ-type, owing to a highly regular {Bi₆} substructure causing a non-localizable molecular orbital of \(f_{z^3}\)-like symmetry.

Radical-mediated functionalization streamlines access to complex synthetic targets. Now, a sulfonium-based donor–acceptor pair enables photoinduced charge-transfer interactions to access electronically diverse aryl radicals. Reaction with enol ethers or isocyanide provides a metal-free method for arene functionalization.

The nitrogen reduction reaction is an extremely valuable but energy-intensive process. Now, a coordination polymer based on a [Zn–N₂–Zn] unit has been shown to promote the formation of ammonia under ambient conditions by a photocatalytic reaction. The N₂ moieties within the framework are reduced, creating unsaturated [Zn²⁺···Zn⁺] intermediates that are able to capture external N₂ and sustain the cycle.

The transition state, a transient species where bond transformation occurs, fundamentally controls reaction dynamics. This important species can be probed through the photodetachment of an anionic precursor, as has now been shown in the F + NH₃ reaction. A combination of theory and experiment reveals resonances that span the transition state.

The strong regiochemical preferences of electrophilic aromatic substitution have played a key role in defining the diversity of accessible chemical space. Now, it has been shown that the electrophilic arylation of phenols can be achieved at the electronically disfavoured meta-position via a formal 1,2-migration of a key σ-complex intermediate.

Direct oxidative methods for the enantioselective synthesis of heterobiaryl compounds that exhibit axial chirality remain elusive. Now, the use of an iron catalyst in the presence of a chiral PyBOX ligand and an oxidant enables the direct coupling of naphthols and indoles with high levels of enantio- and cross-selectivity.

Enzymes with identical sequences of amino acids can display varying activities when encoded with mRNA with different properties, but why this is the case has been a mystery. Now, it has been shown that synonymous mutations in mRNA alter the partitioning of proteins into long-lived soluble misfolded states with varying activities.

Photoactivation of EDA complexes was previously limited to electronically biased partners to secure productive charge-transfer interactions. Now, the participation of triarylsulfonium salts—formed by selective C–H sulfenylation—in photoactive EDA complexes with catalytic triarylamine donors provides a site-selective and metal-free strategy for the generation of aryl radicals and the formal C–H functionalization of native arenes.

Interlocked shape-persistent organic cages are rare structures and the majority are formed using π-stacking as the driving force. Now it is shown that weak dispersion interactions—which are modulated by changing the 1,4-substituents of the constituent dialdehyde linkers—can be used to form interlocked dimeric and trimeric catenated cages.

The light-driven conversion of abundant resources such as CO₂ and H₂O into chemical fuels for energy storage is crucial to end our dependence on fossil fuels. This Review highlights how molecular catalysts and photosensitizers can be grafted onto metal–organic frameworks to combine the advantages of both classes of compounds. Different synthetic strategies are discussed, along with their advantages and limitations.

The synthesis of cyclic polymers remains challenging. Now a trifunctional B-P-B frustrated Lewis pair has been shown to enable easy access to cyclic acrylic polymers through a bimolecular mechanism. These cyclic polymers have enhanced thermodynamic properties compared with their linear counterparts, while maintaining high chemical recyclability.

Polyketide natural products often contain common repeat motifs that are synthesized using iterative processes. Now a masked 1,3-diol motif, generated by a two-step process based on boronic ester homologation, has enabled the efficient iterative synthesis of polyacetates, including bahamaolide A. In addition to oxidation, the 1,3-polyboronic esters were shown to undergo various stereospecific transformations.