Robby Vroemans

Nature Chemistry, Published online: 28 March 2024; doi:10.1038/s41557-024-01470-8

Nature Synthesis, Published online: 27 March 2024; doi:10.1038/s44160-024-00515-7

Publication date: Available online 20 March 2024

Source: Chem

Author(s): Qiang Wang, Haifeng Qi, Yujing Ren, Zhusong Cao, Kathrin Junge, Rajenahally V. Jagadeesh, Matthias Beller

An electrochemical dehydrative reaction of dicarboxylic acids to their cyclic anhydrides is presented. The electrochemically generated anhydrides can be directly employed for amidation reactions. The mechanism of the reaction was investigated by ¹⁸O isotope labeling, revealing the formation of sulfate during electrolysis.

Abstract

An intramolecular electrochemical dehydration reaction of dicarboxylic acids to their cyclic anhydrides is presented. This electrolysis allows dicarboxylic acids as naturally abundant, inexpensive, safe, and readily available starting materials to be transformed into carboxylic anhydrides under mild reaction conditions. No conventional dehydration reagent is required. The obtained cyclic anhydrides are highly valuable reagents in organic synthesis, and in this report, we use them in-situ for acylation reactions of amines to synthesize amides. This work is part of the recent progress in electrochemical dehydration, which – in contrast to electrochemical dehydrogenative reactions for example – is an underexplored field of research. The reaction mechanism was investigated by ¹⁸O isotope labeling, revealing the formation of sulfate by electrochemical oxidation and hydrolysis of the thiocyanate-supporting electrolyte. This transformation is not a classical Kolbe electrolysis, because it is non-decarboxylative, and all carbon atoms of the carboxylic acid starting material are contained in the carboxylic anhydride. In total, 20 examples are shown with NMR yields up to 71 %.

Nature Synthesis, Published online: 26 March 2024; doi:10.1038/s44160-024-00499-4

Publication date: 15 April 2024

Source: Molecular Catalysis, Volume 559

Author(s): Jie Xu, Qiqi Li, Tianlin Ma, Yujie Wang

Publication date: 15 June 2024

Source: Coordination Chemistry Reviews, Volume 509

Author(s): Sem Bleus, Wim Dehaen

Abstract

A Mitsunobu process performed under neat grinding conditions, using a mixer mill, is reported. It proceeds in the absence of reaction solvent and in short reactions times (10–20 min). A broad substrate scope encompassing primary and secondary alcohols, as well as oxygen, nitrogen, sulfur, and carbon-centered nucleophiles is demonstrated. Application to the functionalization of a selection of APIs is shown, also. The developed process is amenable to scale up on a planetary ball-mill, yielding over 2 grams of product. Finally, a representative alcohol is inverted with excellent stereoselectivity.

A straightforward and ligand-free manganese-catalyzed protocol for the chemo- and stereoselective hydroborylation of alkynes with HBpin is demonstrated. This atom-economical reaction is highly selective for the synthesis of (E)-alkenylboronates, and tolerates important functionalities, including halides, ether, alkenyl, silyl and thiophenyl groups. A preliminary mechanistic study supports the involvement of a metal-hydride intermediate.

Abstract

Developing simple and benign protocols for synthesizing alkenylboronates is crucial as they are synthetically valuable compounds in various organic transformations. In this work, we report a straightforward ligand-free protocol for synthesizing alkenylboronates via atom-economical hydroboration of alkynes with HBpin catalyzed by a manganese salt. The reaction shows a high level of chemo and regioselectivity for the terminal alkynes and exclusively produces E-selective alkenylboronates. The hydroboration scope is vast, with the resilience of a range of synthetically beneficial functionalities, such as halides, ether, alkenyl, silyl and thiophenyl groups. This reaction proceeds through the involvement of a metal-hydride intermediate. The developed alkenylboronate can be smoothly converted to useful C-C, C-N and C-I bond-forming reactions.

The 100/100 world of perfumes: Perfumery is currently experiencing its most radical change since the introduction of synthetic vanillin 150 years ago: The transition to 100 % renewable and 100 % biodegradable ingredients. In the Review by P. Kraft and co-workers (DOI: 10.1002/chem.202400006), the reader can learn about the impact that this has on the different fragrance families, and snoop around, from sustainable santals derived from campholenic aldehyde, via a paradisaic pear from itaconic acid, a muguet odorant from oranges, and new routes to the odor principle of ambergris, to musks from crude sulfate turpentine.

This review categorizes MOFs-derived nanomaterials, including nanocarbons and nanometal oxides. Subsequently, the recent research progress on MOFs-derived nanomaterials in photocatalytic water splitting for H₂ production, photocatalytic CO₂ reduction, and photocatalytic water treatment and their corresponding mechanisms are summarized. Finally, the challenges and further directions of MOFs-derived nanomaterials in photocatalytic reactions are proposed.

Abstract

Harnessing low-density solar energy and converting it into high-density chemical energy through photocatalysis has emerged as a promising avenue for the production of chemicals and remediation of environmental pollution, which contributes to alleviating the overreliance on fossil fuels. In recent years, metal-organic frameworks (MOFs) have gained widespread application in the field of photocatalysis due to their photostability, tunable structures, and responsiveness in the visible light range. However, most MOFs exhibit relatively low response to light, limiting their practical applications. MOFs-derived nanomaterials not only retain the inherent advantages of pristine MOFs but also show enhanced light adsorption and responsiveness. This review categorizes and summarizes MOFs-derived nanomaterials, including nanocarbons and nanometal oxides, providing representative examples for the synthetic strategies of each category. Subsequently, the recent research progress on MOFs-derived materials in photocatalytic applications are systematically introduced, specifically in the areas of photocatalytic water splitting to H₂, photocatalytic CO₂ reduction, and photocatalytic water treatment. The corresponding mechanisms involved in each photocatalytic reaction are elaborated in detail. Finally, the review discusses the challenges and further directions faced by MOFs-derived nanomaterials in the field of photocatalysis, highlighting their potential role in advancing sustainable energy production and environmental remediation.

Visible light photocatalysis is an important tool in organic synthesis, enabling the clean and selective generation of reactive intermediates. Current precious metal-based photocatalysts face limitations like cost and toxicity, fueling the search for alternatives like porous organic polymers (POPs). This review examines POPs’ role as photocatalysts in organic synthesis, discussing representative materials, mechanisms, comparisons with other photocatalysts, and future prospects.

Abstract

Concerns about increasing greenhouse gas emissions and their effect on our environment highlight the urgent need for new sustainable technologies. Visible light photocatalysis allows the clean and selective generation of reactive intermediates under mild conditions. The more widespread adoption of the current generation of photocatalysts, particularly those using precious metals, is hampered by drawbacks such as their cost, toxicity, difficult separation, and limited recyclability. This is driving the search for alternatives, such as porous organic polymers (POPs). This new class of materials is made entirely from organic building blocks, can possess high surface area and stability, and has a controllable composition and functionality. This review focuses on the application of POPs as photocatalysts in organic synthesis. For each reaction type, a representative material is discussed, with special attention to the mechanism of the reaction. Additionally, an overview is given, comparing POPs with other classes of photocatalysts, and critical conclusions and future perspectives are provided on this important field.

The terpolymer of CO₂, 1,3-butadiene and epoxides is synthesized by cationic ring-opening copolymerization of α-ethylidene-δ-vinyl-δ-valerolactone (EVL), an intermediate derived from CO₂ and 1,3-butadiene, with epoxides. The resulted poly(ester-ether) with moderate molecular weight bears all the C=C double bonds derived from 1,3-butadiene, enabling post-polymerization modification and functionalization. Photoinitiated crosslinking through these preserved C=C double bonds produces network with fluorescence and degradation properties.

Comprehensive Summary

The utilization of carbon dioxide (CO₂) as a C1 feedstock is consistently attractive, especially in the preparation of sustainable polymeric materials. In this contribution, a terpolymer of CO₂, 1,3-butadiene (BD) and epoxide is synthesized by scandium triflate catalyzed cationic ring-opening copolymerization of α-ethylidene-δ-vinyl-δ-valerolactone (EVL), an intermediate derived from CO₂ and BD, with epoxides. The obtained terpolymer with a CO₂ content of 22 mol% has a number-average molecular weight (M _n) up to 7.8 kg/mol and a dispersity (Đ) of 2.4. The reactivity ratios of EVL and cyclohexene oxide (CHO) are determined as 0.01 and 1.07, respectively, suggesting random characteristic of the terpolymer. The preserved C=C double bonds from BD allow for the further modification of the terpolymer by photoinitiated crosslinking. The yielded networks are fluorescent and degradable. This method offers enhanced versatility to the synthesis and additional functionalization of CO₂-based polymers.

Publication date: 1 June 2024

Source: Coordination Chemistry Reviews, Volume 508

Author(s): Arash Ebrahimi, Lukáš Krivosudský, Alexey Cherevan, Dominik Eder