Marnix van der Kolk

Nature, Published online: 12 March 2024; doi:10.1038/d41586-024-00759-5

Pay for trees with carbon credits to deliver urban green spaces for all

A model for common disease both satisfying and obvious -- or is it?

Nature, Published online: 14 February 2024; doi:10.1038/d41586-024-00410-3

The animals’ shenanigans hint that mischievous play evolved well before Homo sapiens did.

Halogen atom transfer (XAT) from alkyl halides is a mild and selective way to make radicals for use in bond formation, and aryl radicals have emerged as effective “abstractors.” Here, we introduce sulfonium salts as convenient sources of the aryl radicals needed for XAT and show how complexation with carbonate and irradiation with visible light can be used to activate them. To showcase our approach, we describe divergent, light-mediated couplings of alkyl iodides with isocyanides to afford important nitriles or amides.

Collecting and processing sea-squirts (aka tunicates, ascidians) at Carrie Bow research Station, Belize.

This concept article highlights the metal-catalyzed Borrowing Hydrogen (BH) annulation strategy for the preparation of saturated aza-heterocycles from diols and triols. Special attention will also be devoted to stereocontrol issues for the preparation of chiral N-heterocycles.

Abstract

Borrowing hydrogen (BH) has reached a wide attention from the chemistry community as a new opportunity to construct efficiently C−N bond (as well as C−C or C−S bond). This straightforward strategy is usually supported by relevant organometallic catalysts, involved in the dehydrogenation-reduction processes. This concept highlights specifically the application of the borrowing hydrogen to the preparation of saturated aza-heterocycles (piperidines, pyrrolidines and piperazines) extensively present in high-added value molecules of pharmaceutical industry over the last 40 years using homogenous catalysis in particular. A focus will be given to the appropriate metals (Ru, Ir and more recently earth-abundant metals) used for this transformation. An extension to chiral induction in order to prepare enantiopure N-heterocycles will be also reported.

Publication date: February 2024

Source: Journal of Catalysis, Volume 430

Author(s): Carlos P. Silva, Carolina P. Candia, Mauricio Paredes, Elizabeth Imbarack, Fabian Martínez-Gómez, Camila F. Olguín, Geraldine Jara, José H. Zagal, Jorge Pavez, Nicolás Agurto

In the heat of 2022, amidst my PhD studies, I explored deeper aspects of sports psychology. Witnessing athletes' sacrifice for success, I embarked on empirical research, navigating obstacles to uncover hidden truths. Join me on this journey where perseverance meets understanding.

Abstract

Dehydrogenative coupling (DC) is an attractive approach to constructing new C−N bonds using alcohols as electrophiles. In ‘hydrogen-borrowing’ variants of DC, the H₂ liberated can be used to re-hydrogenate unsaturated intermediates to produce saturated products. Here, we show how so-generated H₂ can also be used to replace fluorine atoms with hydrogens in CF₃ groups in a tandem dehydrogenative coupling/hydrodefluorination process.

Time for a change. The use of N,N-dimethyl formamide (DMF) will be restricted in the European Union from December 2023 because of its reproductive health hazard. Now is the time to replace DMF in fundamental research so that future processes are not reliant on an obsolete, hazardous solvent.

Abstract

As of December 2023, the use of common solvent N,N-dimethyl formamide (DMF) will be restricted in the European Union because of its reproductive health hazard. Industrial facilities must comply with stricter exposure limits, and researchers are recommended to find alternative solvents. Here we explain the restrictions on DMF, which disciplines are affected, and how to substitute DMF to keep research and development commercially relevant.

Nature Chemistry, Published online: 25 January 2024; doi:10.1038/s41557-023-01429-1

While saturated N-heterocycles are widespread motifs in drug discovery, the seven-membered ring azepane is highly underrepresented. Now nitroarenes have been validated as competent substrates for azepane synthesis through conversion into singlet nitrenes for ring enlargement via N insertion and hydrogenolysis. This enables a highly versatile access towards polysubstituted azepanes in just two steps.

Perfluoroalkyl substances (PFAS) are persistent environmental pollutants. In this work, we summarized recent progress on the chemical defluorination of PFAS via cleavage of unactivated C−F bonds in longer perfluoroalkyl groups under mild conditions (~150 °C). In addition to classic reductive defluorination, the strategies featuring Lewis acidic activation and transient generation of an unsaturated bond are described.

Abstract

Perfluoroalkyl substances (PFAS) have been recognized as environmental pollutants. Hence, their efficient and mild destruction is a significant research interest. While many research articles and review papers have reported the cleavage of the C(sp²)−F bonds, single C(sp³)−F bond, and CF₃ groups in PFAS, in this study, limited and emerging examples of a longer perfluoroalkyl group containing at least one repeating unit of 1,1,2,2-tetrafluoroethylene was focused. In this Concept, we summarized recent progress on the chemical defluorination of PFAS via the cleavage of unactivated C(sp³)−F bonds in longer perfluoroalkyl groups under mild conditions (~150 °C). In addition to classical reductive defluorination, strategies featuring Lewis acid activation and the transient generation of an unsaturated bond were described.

Transition-metal-catalysed transfer hydrogenation using non-toxic, low cost and renewable biomass as hydrogen donors represents a sustainable and promising approach for the reduction of organic compounds. In this context, glycerol and carbohydrates are attractive hydrogen donors. In this review, we explore various catalytic systems that have been reported for reducing various unsaturated compounds, as well as the advantages and challenges associated with biomass in transfer hydrogenation reactions.

Abstract

Catalytic transfer hydrogenation is a practical approach for reduction of various unsaturated compounds and an alternative to pressurised hydrogenation and traditional metal hydride reagents. Among the various hydrogen donors, biomass such as glycerol and carbohydrates received considerable attention for the reduction reactions due to their non-toxic, eco-friendly and renewable nature. The present review addresses the development of homogeneous and heterogeneous catalysts for the transfer hydrogenation of carbonyl compounds, alkenes, alkynes, nitro compounds, CO₂ etc. using glycerol and carbohydrates as potential hydrogen donors.

Nature Chemistry, Published online: 18 January 2024; doi:10.1038/s41557-023-01428-2

Skeletal editing enables diversification of compounds not possible by applying peripheral editing strategies. Now, a catalyst-free atom-pair swap strategy for pyridine editing has been developed via one-pot sequential dearomatization, cycloaddition and rearomative retrocyclization. Benzenes and naphthalenes with precisely installed functional groups are produced, and the mild conditions enable late-stage skeletal diversification of pyridine cores.

Nature, Published online: 16 January 2024; doi:10.1038/d41586-024-00147-z

In a survey of 2,700 AI experts, a majority said there was an at least 5% chance that superintelligent machines will destroy humanity. Plus, how medical AI fails when assessing new patients and AI discovery suggests that human fingerprints aren’t unique.