Marnix van der Kolk

Nature, Published online: 13 April 2023; doi:10.1038/d41586-023-01029-6

Models and laboratory swings show the precise motions needed to maximize movement.

The instrumental analysis of reaction mixtures is usually the rate-determining step in the optimization of chemical processes. Traditionally, reactions are analyzed by gas chromatography (GC), high-performance liquid chromatography (HPLC), or quantitative nuclear magnetic resonance (qNMR) spectroscopy on high-field spectrometers. However, chromatographic methods require elaborate work-up and calibration protocols, while high-field NMR spectrometers are expensive to purchase and operate. We herein disclose an inexpensive and highly effective analysis method based on low-field benchtop-NMR spectroscopy. Its key feature is the use of fluorine-labeled model substrates which, due to the wide chemical shift range and high sensitivity of 19F, enables separate, quantitative detection of product and by-product signals even on low-field, permanent magnet spectrometers. An external lock / shim device obviates the need for deuterated solvents, permitting the direct, non-invasive measurement of crude reaction mixtures with minimal work-up. The low field-strength allows a homogeneous excitation over a wide chemical shift range, minimizing systematic integration errors. The addition of the correct amount of the non-shifting relaxation agent Fe(acac)3 minimizes relaxation delays at full resolution, reducing the analysis time to 32 seconds per sample. The correct choice of processing parameters is also crucial. A step-by-step guideline is provided, the influence of all parameters is discussed, and potential pitfalls are highlighted. The wide applicability of the analytical protocol for reaction optimization is illustrated by three examples: a Buchwald-Hartwig amination, a Suzuki coupling, and a C–H functionalization reaction.

Nature, Published online: 06 April 2023; doi:10.1038/d41586-023-00984-4

Researchers describe how listening to music at work can boost (or hamper) productivity, and share the tunes that keep them focused.

Nature, Published online: 31 March 2023; doi:10.1038/d41586-023-00966-6

Thirsty or injured plants make ultrasonic clicks. Plus, a biodegradable glass made from proteins, and Tyrannosaurus rex had lips.

Nature Synthesis, Published online: 29 March 2023; doi:10.1038/s44160-023-00273-y

Solar-driven photosynthesis offers a sustainable approach to directly producing hydrogen peroxide from oxygen and water but remains inefficient owing to the low photocatalytic efficiency of reported photocatalysts. Now, a Ga–N5 atomic site on macroporous inverse-opal-type carbon nitride is introduced for the visible-light-driven photosynthesis of hydrogen peroxide with a solar-to-chemical conversion efficiency of 0.4%.

Alternative sources for polymeric materials have been sought in the past few years to reduce our dependence on fossil feedstock. We report the catalytic carbonylation of acrylic acid, a platform chemical that can be bio-sourced, as a new pathway toward the formation of a useful monomer to polyesters, namely succinic anhydride. The novel system reported herein tackles the difficult carbonylation of unsaturated carboxylic acids through the utilization of an Earth-abundant metal catalyst, [Co2(CO)8], in presence of a bidentate ligand, 1,2-bis(dicyclohexylphosphino)ethane (dcpe), and H2. We investigated the influence of the reaction conditions through the variations of metal, ligand, temperature, pressure, and gas composition variations. The carbonylative ring-closure of acrylic acid was successfully obtained in high yield and selectivity toward the formation of succinic anhydride using mild conditions (90 °C and 16 bar of CO/H2 95:5).

Oxygen-substituted arenes not only commonly exist in biologically important molecules, but also serve as a versatile handle to install other functional groups. However, to date it remains challenging to install oxygen groups directly and site-selectively to common aromatic compounds, especially when additional arene functionalization is simultaneously required. Current arene C−H oxidation strategies generally require directing groups to control site-selectivity and/or use strong oxidants, whereas other approaches need precisely pre-functionalized substrates. While the palladium/norbornene (Pd/NBE) cooperative catalysis is promising for site-specific arene vicinal difunctionalization through simultaneous reactions with an electrophile and a nucleophile, respectively, at the ortho and ipso positions, the electrophile scope has been limited to species based on relatively “soft” elements, such as carbon, nitrogen, and sulfur. To shift the Pd/NBE-catalysis paradigm, here we report the development of an ortho oxygenation reaction with readily available aryl halides to rapidly deliver diverse methyl aryl ethers. The coupling of the “hard” oxygen-electrophile is enabled by a stable, polarity reversed, conformationally pre-distorted N−O reagent and facilitated by a C7-bromo-substituted NBE mediator. Mechanistic studies reveal a unique SN2-type pathway between the N−O reagent as the oxygen electrophile and an electron-rich Pd(II) nucleophile. This new C−H oxygenation reaction allows streamlined synthesis of complex bioactive compounds containing methyl aryl ethers and provides an efficient modular approach to access underrepresented benzenoid substitution patterns that are challenging to prepare otherwise.

Nature, Published online: 10 March 2023; doi:10.1038/d41586-023-00703-z

Matthias Rillig’s foray into film-making has helped him to identify the research and management skills he needs to work on.

Publication date: May 2023

Source: Journal of Catalysis, Volume 421

Author(s): Maurice Vennewald, Nina Michelle Sackers, Andree Iemhoff, Isabella Kappel, Claudia Weidenthaler, Ansgar Meise, Marc Heggen, Rafal E. Dunin-Borkowski, Luke Keenan, Regina Palkovits

Nature, Published online: 06 March 2023; doi:10.1038/d41586-023-00674-1

Emojis are part of a science communicator’s arsenal. Computational chemist Andrew White describes how and why he submitted an application.

Nature, Published online: 28 February 2023; doi:10.1038/d41586-023-00556-6

100 years of dinosaur eggs

Nature Synthesis, Published online: 09 January 2023; doi:10.1038/s44160-022-00207-0

Single-atom catalysts (SACs) can increase atom efficiency and show remarkable catalytic performance compared with their bulk analogues; however, direct fabrication in high yield is challenging. Now, a 3D printing approach realizes the controlled and precise synthesis of SACs with desired geometries.

Exocyclic tetra-substituted carbon-carbon double bonds in uniform configuration and creation of tertiary or quaternary stereogenic centers in a diastereoselective or enantioselective manner – these are structural motives that are accessible by a cascade consisting of a Heck reaction and subsequent Suzuki-Miyaura coupling with suitable palladium catalysts that guarantee a high degree of stereoselectivity.

Abstract

Palladium catalysis enables efficient and versatile domino reactions that are initiated by an intramolecular Mizoroki-Heck reaction and then terminated by a Suzuki-Miyaura coupling. The stereochemistry of this cascade is concerned under three aspects: Firstly, as stereoselective formation of carbon−carbon-double bonds, when the initial carbometalation occurs at an alkyne moiety. Secondly as diastereoselective and thirdly enantioselective formation of stereogenic carbon centers when the intramolecular Heck step is directed to an alkene moiety. Valuable protocols lead to – otherwise not easily accomplished – stereo control in the formation of tri- and tetra-substituted double bonds according to the first conception. The diastereoselective versions permit the formation of multiple stereocenters in mono- and polycycles. Enantioselective protocols were developed only recently. The fact that the newly created stereocenters are highly-substituted, tertiary or quaternary ones, makes the methods that are presented in this review useful and versatile tools in synthesis.

Publication date: January 2023

Source: Journal of Catalysis, Volume 417

Author(s): Jiaqi Wang, Yun Yuan, Kaiyuan Ren, Bingqing Wang, Zhaohui Li

The first use of 1,1-bis[(pinacolato)boryl]methane as the terminating reagent in Catellani reaction is reported. The reaction provides an efficient method to access benzylboronates, which are useful organoboron compounds in organic synthesis.

Abstract

We report herein the application of 1,1-bis[(pinacolato)boryl]methane as a new type of terminating reagent to realize three-component coupling reaction with aryl iodide and different electrophiles. A series of ortho-disubstituted benzylboronates can be synthesized and the ortho-substituent can be varied by using bromoacetic esters or O-benzoyl hydroxylamine as electrophiles with slightly modified reaction conditions. The reaction shows good functional group tolerance and the obtained benzyl boronate products can be easily transformed to various synthetically useful compounds.

Here, we report a comprehensive three-component reaction (3CR) of ethylene with two different phosphorus precursors for the synthesis of symmetric and unsymmetric 1,2-bis(diphenylphosphino)ethane (DPPE) derivatives using the artificial force induced reaction (AFIR) method.