Marnix van der Kolk

Nature, Published online: 13 February 2026; doi:10.1038/d41586-025-03967-9

Preprint repositories and conference organizers are having to counter a tide of ‘AI slop’ submissions.

A less hindered and highly nucleophilic N-heterocyclic carbene (NHC) boryl anion is generated at room temperature by reacting sp²–sp³ diboron reagent (NHC)BH₂Bpin with KO ^t Bu. This highly reactive anion demonstrates broad reactivity with various electrophiles, including those traditionally considered inert, enabling their efficient borylation. DFT calculations confirm the anion's high nucleophilicity and offer insights into reaction pathways.

ABSTRACT

Due to its high activity, the synthesis or generation of the N-heterocyclic carbene (NHC) boryl anion remains challenging, with only limited methods available. Traditional stabilization through bulky ligands or aromatic systems restricts its reactivity as a boron synthon. In this work, we present a straightforward strategy for the in situ generation of an NHC boryl anion at room temperature through the reaction of neutral sp²–sp³ diboron reagent (NHC)BH₂Bpin with KO ^t Bu. This less sterically hindered and strongly nucleophilic boryl anion demonstrates broad reactivity with diverse electrophiles, including those that are unreactive with other types of boryl anions or traditional diboron reagents. These nucleophilic borylation reactions enable the synthesis of a diverse array of four-coordinate organoboron compounds. Detailed mechanistic studies and DFT calculations confirm the intermediacy of the NHC boryl anion and provide clear insights into the reaction pathways for the newly discovered reactivities.

Polyethylene-like copolymers with benchmark properties are prepared by embedding latent cyclobutene mechanophores to overcome PE's end-of-life limits. The mechanophores are inert in service but are selectively opened by solvent-free ball milling to yield well-defined telechelic oligomers. After ethanolysis/hydrogenation, these oligomers are repolymerized to cross-linked PE with commercial-grade properties, enabling a practical closed-loop circularity.

ABSTRACT

Polyethylene (PE) materials are indispensable to modern infrastructure due to their exceptional thermal, mechanical, and chemical resilience. However, the same properties that make these materials durable also render them environmentally persistent and unrecyclable by conventional means, posing a critical sustainability challenge. Here, we report a mechanochemically triggered, chemically recyclable PE-like system that enables the closed-loop recycling of cross-linked polyethylene (XLPE). Through palladium-catalyzed coordination copolymerization of ethylene with the cyclobutene-fused ester (CBE) comonomer, polar PE-like materials with tunable properties are achieved. Upon optimal mechanical activation in the presence of a radical inhibitor, the CBE units undergo ring opening, installing ester linkages into the polymer backbone. Notably, the high crystallinity of copolymers with low CBE content enables ball-milling to achieve activation efficiency comparable to cryo-milling. Subsequent ethanolysis of ester linkages cleanly converts the initial copolymer into multifunctional oligomers, which can be repolymerized after hydrogenation via transesterification to yield a recyclable XLPE with properties comparable to a commercial analogue. This work demonstrates a robust platform for reconciling the durability and recyclability of polyethylene, offering a transformative route toward sustainable polyolefins.

Acid-generated carbocations are selectively trapped by sulfide and selenide donor molecules in the form of onium salts. Through manipulation of one of the donor's substituents, these onium salts undergo elimination towards the corresponding transchalcogenation products. This strategy enables the shuttling of toxic S and Se moieties, while providing a rational platform to improve reaction selectivity in carbocation functionalization.

ABSTRACT

Introducing functionalities via acid-mediated carbocation chemistry is conceptually straightforward, but typically lacks in selectivity and broad-scale applicability, which is further hampered by the need for toxic reaction partners. Here, we show that small S- and Se-based functionalities can be selectively and safely introduced into feedstock molecules via acid-catalyzed transchalcogenation reactions. A designable y-keto donor compound delivers the functionality through the formation of a trialkyl chalcogenonium intermediate that is prone to elimination in conjunction with the acid catalyst and its counteranion. We demonstrate how this strategy enables chemo-, regio-, and stereoselective construction of C(sp³)─S and ─Se bonds, offering clear advantages over classical acid-catalyzed carbocation functionalization.

Decarboxylative oxygenation reactions leverage abundant carboxylic acids to synthesize useful oxygenated products. Herein, we present a photoexcited nitroarene-mediated approach for the practical, economical, and anaerobic decarboxylative oxygenation of carboxylic acids. Under visible-light irradiation, the commercially available nitroarene dually enables direct homolysis of strong carboxylic acid O–H bonds and subsequent oxygen atom transfer with the resulting alkyl radicals. Mechanistic experiments, including DFT and carbon-13 isotope studies, elucidate the key PCET process, laying the groundwork for the future utility of this powerful reagent class.

Nature, Published online: 28 January 2026; doi:10.1038/d41586-026-00273-w

New data are revealing the benefits of exercising little and often.

Nature, Published online: 20 January 2026; doi:10.1038/d41586-026-00151-5

Super-high protein diets are promoted by influencers, but the science shows that there are limits to how much your body can use.

Mechanochemistry, from the ancient mortar and pestle to modern ball milling, offers sustainable, solvent-free reactions with unique selectivity while reducing emissions and costs. This review traces its history; highlights time-resolved in situ monitoring and computational insights into mechanisms; explores synergies with heat, light, electricity, and sound; and discusses emerging applications in the origins of life, supramolecular intermediates guiding the formation of covalent bonds, and direct mechanocatalysis. Emphasizing upscaling and digital integration, it highlights the transformative potential of mechanochemistry for forming the next-generation sustainable chemical industry.

Nature, Published online: 19 January 2026; doi:10.1038/s41586-026-10131-4

Collective intelligence for AI-assisted chemical synthesis

We report a robust, metal-free and scalable synthesis of stable BF₂ boracycles via directed ortho CH borylation, delivering isolable, shelf-stable reagents without chromatographic purification. These BF₂ boracycles exhibit unique and tunable reactivity, enabling highly selective ipso-functionalization across a broad range of transformations. Their exceptional stability, wide substrate scope, and superior reactivity establish BF₂ boracycles as powerful alternatives to conventional organoboron reagents for pharmaceutical and radiochemical applications.

Abstract

The development of new boron reagents continues to play a crucial role in advancing modern organic synthesis, particularly in C–H functionalization and cross-coupling reactions. Herein, we report a metal-free, robust, and scalable multigram protocol for the synthesis of stable BF₂ boracycles that require no column chromatography, providing a practical and efficient route to access this valuable boron species. The BF₂ boracycles exhibit enhanced stability and reactivity, making them highly versatile intermediates for late-stage diversification. They undergo ipso-substitution to afford a wide array of derivatives, including halogenated (e.g., radioiodinated), hydroxylated, and azidated products. Furthermore, they display excellent reactivity in Suzuki–Miyaura cross-coupling reactions, enabling both C(sp²)─C(sp²) and C(sp²)─C(sp³) bond formation. These results underscore the utility of BF₂ boracycles as powerful tools for selective functionalization in pharmaceutical synthesis and beyond. Our work represents a significant advancement in organoboron chemistry, offering both a streamlined synthetic approach and broad applicability for complex molecule construction.