Sodium metal is of interest for high-energy-density batteries, but the lack of large-area ultrathin sodium metal foils hinders research. Here a metre-length, ultrathin (≤50 μm), mechanically strengthened sodium metal foil is fabricated by a roll-to-roll calendaring process with interfacial lubrication and functional modification.

The sustainable synthesis of carbohydrates from CO₂ is challenging due to the complexity of controlled CO₂ reduction. Here a two-step method for the sustainable synthesis of C₅₊ carbohydrates is reported. CO₂ is initially fixed into hydroxymethanesulfonate, which is then used as a formaldehyde surrogate in a formose reaction to synthesize C₅₊ carbohydrates.

The precision synthesis of uniform oligoethylenes with chain lengths of up to 576 carbon atoms is achieved via an iterative growth approach based on the Julia–Kocienski reaction. The oligoethylenes are used as building blocks to prepare high-density polyethylene-like materials with regularly spaced ester linkages.

The precise manipulation of unfunctionalized hydrocarbons remains a fundamental challenge in chemical synthesis and catalysis. Here an organocatalytic asymmetric hydroxylation of bicyclobutanes with alcohols is disclosed, enabling efficient access to tertiary cyclopropylcarbinyl ethers with high enantioselectivity (up to 98:2 e.r.).

The use of benzene ring contraction in chemical synthesis is challenging due to the need to disrupt aromaticity and generate highly strained intermediates. Now, a photothermal ring contraction reaction for the synthesis of multisubstituted fused pyridines is reported, from arylhydrazines and carbonyl compounds, via benzene ring contraction.

Concerted 1,3-alkyl shifts are often challenging due to antiaromatic transition states and geometric strain. Now, a formal 1,3-migration can be achieved through two consecutive 1,2-shifts—a Pd(II)-catalysed semi-pinacol rearrangement followed by a 1,2-C/Pd(IV) dyotropic rearrangement. This two-step process transforms 1-vinylcyclobutanols into fluorinated cyclohexanones or cyclohexenones, depending on the reaction conditions.

Macrocyclization typically proceeds via thioesterase mediation in type I polyketide synthases. Now, using genome mining and crystallographic analysis, an alternative mechanism for stereoselective macrocyclization in the akaeolide biosynthetic pathway is reported. The mechanism is proposed to proceed via an iminium-catalysed tandem Michael addition and Knoevenagel condensation, using nuclear transport factor 2-like enzymes.

An artificial intelligence-driven robotic chemist that integrates generative machine-learning models incorporating spectroscopic descriptors with automated experimentation is developed, enabling the inverse design of high-entropy catalysts and offering a generalizable strategy for the design of diverse complex materials.

A boryl-isodiazomethyl anion featuring a bent eneyne-type B=N–N≡C scaffold is isolated and structurally characterized. The highly nucleophilic boron-bound nitrogen centre makes this species an effective synthon of boryl-nitrene for concerted CN⁻/CO exchange and metathesis reactions with C=O, C=S and C=N bonds via cleavage of the N–N bond.

A photocatalytic synthetic route to deuterated N-heteroarenes over an atomically dispersed palladium photocatalyst in D₂O is developed. By recycling used D₂O and photocatalyst, up to 1.157 kg of deuterated N-heteroarenes can be obtained using only 4.5 litres of D₂O (19.7 equiv.).

In this Editorial, we reflect on some of the striking covers that Nature Synthesis published in 2025 and highlight the research they represent.