Robby Vroemans

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

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

Publication date: 12 April 2024

Source: Tetrahedron Letters, Volume 139

Author(s): Fen Wang, Shouliang Yang, Alberto Castanedo, John Braganza, Indrawan McAlpine

The synthesis and gram-scale isolation of the elusive cyanoketenyl anion [NC₃O]⁻ is reported. Despite its cumulene-like structure, it exhibits a bent geometry in the solid state, which is also confirmed by computational studies. The cyanoketenyl anion readily reacts with a series of small molecules such as CO₂, H₂O or NH₃ to form more complex organic compounds, including industrially valuable compounds such as cyanoacetate.

Abstract

Cumulenes and heterocumulenes with three or more cumulative multiple bonds are usually reactive species that serve as valuable building blocks for more complex molecules but tend to isomerize or cyclize and therefore are difficult to isolate. Using a mild ligand exchange reaction at the carbon in α-metalated ylides, we have now succeeded in the synthesis and gram-scale isolation of the elusive cyanoketenyl anion [NC₃O]⁻. Despite its assumed cumulene-like structure and the delocalization of the negative charge across the whole 5-atom molecule, it features a bent geometry with a nucleophilic central carbon atom. Computational studies reveal an ambiguous bonding situation in the anion, which can be illustrated only by a combination of different resonance structures. Nonetheless, the anion features remarkable stability, thus allowing the storage of its potassium-crown ether salt and its application as a highly functional synthetic building block. The cyanoketenyl anion readily reacts with a series of small molecules to form more complex organic compounds, including industrially valuable compounds such as cyanoacetate. This work demonstrated that reactive species can be generated by novel synthesis methods and open up atom-economic pathways to complex compounds from small abundant molecules.

Nature, Published online: 12 March 2024; doi:10.1038/d41586-024-00718-0

A water-stable porphyrinic metal-organic framework (PCN-224) with cooperative hydrophobic and electrostatic adsorption domains have been investigated for removal of perfluorooctane sulfonate and perfluorobutane sulfonate with fast kinetics, high capacities, high selectivity and good recyclability. Mechanism study demonstrates that the exellent performance is due to the merits of orthogonal cationic channel pores, hydrophobic ligands and acidic metal nodes of PCN-224.

Abstract

The removal of toxic poly- and perfluoroalkyl substances (PFAS) as persistent pollutants from wastewater is imperative but challenging for water remediation. Many adsorbents including activated carbon, biochar, and clay minerals have been investigated for PFAS removal, but most of these materials are faced with high cost or/and low efficiency. The use of metal-organic frameworks (MOFs) as sorbents is attractive for efficient removal of PFAS due to their tailor-made structures and high surface areas. Herein, we synthesized, characterized a water stable Zr-based porphyrinic MOF (PCN-224) with cooperative adsorption domains, and demonstrated its excellent capture performance toward perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorobutane sulfonate (PFBS). PCN-224 has maximum uptake capacities of 963, 517, and 395 mg g⁻¹ for PFOS, PFHxS, and PFBS, respectively, which are much higher than that of granular activated carbon. Moreover, coexistent anions (Cl⁻, SO₄ ²⁻) and humic acid have negligible effects on PFOS adsorption. The excellent adsorption performance of PCN-224 toward PFOS is due to the orthogonal cationic channel pores with a diameter of 1.9 nm, the hydrophobic porphyrin units, and the Zr₆ clusters with acidic sites. PCN-224 can be readily regenerated and reused. This work highlights the potential of MOFs with multiple adsorption domains for water remediation.

Synlett
DOI: 10.1055/a-2272-8045

Photoinduced carbamoylation of ethers using isocyanates as amide sources was accomplished under mild and environmentally friendly reaction conditions. A series of isocyanates were tolerated in this protocol to construct α-amide-substituted ether derivatives with desired yields. The method featured broad substrate scope and good functional group tolerance, which could play an important role in the construction of biological molecules with ethers.
[...]

Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/a-2262-9575

Organic fluorophores have consistently garnered significant interest owing to their widespread application across various multidisciplinary research fields. In the realm of biological research, these organic fluorophores find extensive use in diverse applications such as molecular imaging, DNA sequencing, drug discovery, and biosensors. Remarkably, in recent times, organic fluorescent molecules have emerged as pivotal elements in the advancement of organic electronics. Across several reaction pathways developed for constructing and modifying organic fluorophores, transition-metal-catalyzed C–H activation reactions have come across as a dependable and step-economical approach. In this review we discuss various transition-metal-catalyzed C–H activation-based approaches that have been employed to create and modify organic fluorescent molecules which find applications in multidisciplinary research areas.1 Introduction2 Basic Reactions for the Creation of Organic Fluorophores3 Merits and Drawbacks of Classical Reactions in the Creation and Modification of Organic Fluorophores4 C–H Activation/Functionalization Reactions5 C–H Activation Pathways in the Creation and Modification of Organic­ Fluorophores5.1 Electrophilic C–H Activation Reactions5.2 Heteroatom-Directed C–H Activation Reactions6 Conclusion
[...]

Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Fe single atom on nitrogen doped carbon as efficient, bench stable and recyclable catalyst for S-benzyl/alkylation of dithiocarbamates via borrowing hydrogen strategy. A wide range of functional groups are well tolerated and gave the desired dithiocarbamate products in good to excellent yields.

Abstract

Herein we report, the synthesis of single-atom iron on nitrogen-doped carbon as a catalyst for the direct formation of C_sp3−S bond via borrowing hydrogen strategy using alcohols as the alkylating agent. The catalyst was synthesized by encapsulating ferrocene within the ZIF-8 framework, followed by pyrolysis and characterized precisely by FE-SEM, HR-TEM, XPS, Raman, XRD and EXAFS. The catalyst is robust, displayed an excellent reactivity in borrowing hydrogen reaction and could be recycled five times without any appreciable loss in activity.