Research articles

H₂O₂-dependent haem-peroxygenase-catalysed C–H bond oxyfunctionalization reactions have attracted much attention, but elevated concentrations of H₂O₂ are detrimental to the enzyme. Now, it is reported that this biocatalyst can operate via an alternative pathway using O₂ and small-molecule reductants.

Water has been used in organic synthesis as a hydrogen and oxygen source for reductive and oxidative transformations, respectively. Now water is used as both the source of H₂ and formal oxidant in a ruthenium-catalysed hydrogenative oxidation strategy, enabling the synthesis of lactams from N-heteroarenes in a single synthetic step.

The extraction of urea is an important part of wastewater purification and a potential source of valuable fixed nitrogen. Here the authors combine electrocatalytic oxygen reduction with precipitation of urea from urine in the form of a solid peroxide (percarbamide) and demonstrate several potential applications.

The understanding of electrochemical interfaces between polymer electrolytes and metal electrodes, which is critical to many practical devices, remains limited. Now, the interaction between Nafion’s sulfonate groups and platinum and its impact on the oxygen reduction reaction is studied in detail, and a distinct coupled cation–electron transfer mechanism is identified.

Electrolyte cations have been shown to have a strong impact on reactivity in electrocatalytic CO₂ reduction. However, most studies have been performed in an aqueous environment. Here the effect of various alkylammonium cations on CO₂ reduction in aprotic solvents is investigated, with the interfacial electric field induced by the cations shown to be a dominant factor.

Understanding the interplay between solvent, reactant and catalyst is important to advance towards upgrading biomass into useful products, but the process remains challenging. Now a study on guaiacol demethylation in water highlights the substantial shift in catalytic behaviour that occurs when moving from bulk water to the confined space within zeolite channels.

The efficiency of enantioselective sp³ C–H bond oxidation using small synthetic catalysts is usually limited. Now a catalytic system involving a Cu(II)-bound tert-butoxy radical for site-selective C–H bond cleavage achieves allylic and propargylic sp³ C–H oxidation with the C–H substrates as the limiting reagent.

Decarboxylative azidation is a valuable transformation in organic chemistry, but a biocatalytic equivalent remained elusive. Now merging photoredox with metalloenzymatic catalysis enables the enantioselective decarboxylative radical azidation and thiocyanation of N-hydroxyphthalimide esters.

Alkali cations in electrolytes are commonly considered chemically inert species, but their role has recently been called into question. Now, using in situ spectroscopy and molecular dynamics simulations, it is shown that alkali cations couple with intermediates in the oxygen reduction reaction, acting as cocatalysts.

The catalytic mechanism of [Fe]-hydrogenases is not well understood. Now a signal-enhanced nuclear magnetic resonance method based on parahydrogen is introduced to study [Fe]-hydrogenase under turnover conditions in situ, revealing intermediates of the catalytic cycle.

Compatibility issues often limit chemoenzymatic systems. Now it is shown that the proximity between catalytic polymers grafted from the membrane of microorganisms and intracellular heterologous enzymes enhances the reaction rates of a photoenzymatic system, while the coating increases the stability.

The development of catalytic systems for sequestering anthropogenic methane emissions from the atmosphere could potentially reduce global warming. Now, coupling the enzyme alcohol oxidase with an inorganic zeolite generates formaldehyde from methane under ambient conditions with 90% selectivity.

Despite the importance of difluoromethyl (CF₂H)-bearing centres for pharmaceuticals, there is currently no general strategy for the stereoselective introduction of a CF₂H group at chiral centres. Here the authors describe an enantioconvergent difluoromethylation method for racemic alkyl halides to construct such stereocentres.

Electrifying energy-intensive processes is a promising approach for decarbonization. Now, 1,3-butadiene is electrochemically produced from acetylene on I⁻−induced Cu^δ+–Cu⁰ sites with a Faradaic efficiency of over 90% at −0.85 V_SHE and a partial current density of −75 mA cm⁻² at −1.0 V_SHE.

Obtaining high-purity CO requires energy-intensive purification processes. Here metastable fluorite ZrO₂ is prepared that can catalyse thermal and photothermal formic acid dehydration to CO while completely shutting off the impurity-generating dehydrogenation pathway.

Catalysts used for steam methane reforming frequently suffer from deactivation by coking and oxidation. Here an active Cu–Rh plasmonic antenna–reactor photocatalyst is selective and stable under illumination but deactivates under purely thermal conditions. The thermally deactivated catalyst can then be regenerated under illumination.

Anion-exchange membrane water electrolysers have the potential to rival more costly acidic proton-exchange membrane electrolysers, but their performance and efficiency commonly still fall short. Now an anion-exchange membrane water electrolyser is prepared with a NiFe layered double hydroxide catalyst-coated membrane that achieves high current densities above 2 A cm⁻² at 1.8 V and operando X-ray absorption spectroscopy is used to track the formation of the catalytically active γ-LDH phase.

Catalytic conversion of alkenes into carbanion equivalents usually requires stoichiometric reductants. Now an alternative strategy to access alkyl carbanion equivalents from abundant alkenes with the help of visible light photocatalysis is reported and used in four distinct C–C bond-forming reactions.

Heteroatom-substituted C(sp³)-rich polycyclic hydrocarbon rings, isosteric to heterocyclic rings, are not common due to the challenging synthesis. Now a photoredox-catalysed strategy to insert amidyl radicals into bicyclo[1.1.0]butanes is presented, providing direct access to 2-oxa-4-azabicyclo[3.1.1]hept-3-enes.

The replacement of palladium with other metal catalysts in C–C bond-forming reactions is attractive in terms of costs and sustainability. Now an iron-based catalyst is successfully employed in the Suzuki cross-coupling of aryl chlorides with aryl boronic esters activated with tert-butyl lithium.