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Single-pot conversion of furfural (FAL) to alkyl levulinates (ALs) without using molecular hydrogen has been studied over ZSM-5-based Ni−W bimetallic catalysts. The catalyst developed in the present study exhibited excellent catalytic performance towards the production of various ALs from FAL using primary and secondary alcohols as source of hydrogen as well as reactant.

Abstract

A single–pot conversion of furfural (FAL) to alkyl levulinates (AL) without using molecular hydrogen has been studied over ZSM-5-based Ni−W bimetallic catalysts. The metal-metal and metal-support interactions in the bi-metallic catalyst are tailored by adopting appropriate synthesis protocol to conceive the superior catalytic performance. Insights on the structural properties and structure-properties relationship of catalyst is described using the data obtained through various characterization techniques like FTIR, XRD, NH₃-TPD, H₂-TPR, TEM, UV-Vis, and X-ray photoelectron spectroscopy. The catalyst synthesis method is observed to influence catalyst properties and catalytic activity strongly. The present study indicates the formation of Ni−W bimetallic interface enhances the catalytic performance towards AL formation. However, the probability of interface formation is mainly governed by synthesis protocol. The study highlights the importance of selecting a suitable synthesis route to achieve desirable catalyst properties for obtaining enhanced catalytic performance. The Ni/W@ZSM-5 catalyst developed in the present study exhibited excellent catalytic performance towards the production of various ALs from FAL using primary and secondary alcohols as source of hydrogen as well as reactant.

An efficient and environmentally friendly reaction with 1H-benzotriazoleamide and methyl coumalate using DBU as catalyst to obtain arene derivatives in good yields is reported.

Abstract

The DBU-catalyzed benzylation of 1H-benzotriazole amides with methyl coumalate is demonstrated for the synthesis of stilbenes and biaryl derivatives. The transformation involves the base-catalyzed Michael addition of methyl coumalate to the 6π-electrocyclic ring opening decarboxylation aromatization. Furthermore, the novel 2-phenylnaphthalene derivatives showed potent anti-proliferative and anti-invasive activities against H1299 cells.

This proof-of-concept study establishes the viability and generality of mechanophotocatalysis, merging mechanochemistry and photocatalysis to enable solvent-minimized photocatalytic reactions. We demonstrate the transmutation of four archetypal solution-state photocatalysis reactions to a solvent-minimized environment driven by the combined actions of milling, light, and photocatalysts. The chlorosulfonylation of alkenes and the pinacol coupling of aldehydes and ketones were conducted under solvent-free conditions with competitive or superior efficiencies to their solution-state analogues. Furthermore, decarboxylative alkylations are shown to function efficiently under solvent-minimized conditions, while the photoinduced energy transfer promoted [2+2] cycloaddition of chalcone experiences a significant initial rate enhancement over its solution-state variant. This work serves as a platform for future discoveries in an underexplored field, validating that solvent-minimized photocatalysis is generalisable and competitive with solution-state photocatalysis.

Nature, Published online: 10 October 2023; doi:10.1038/d41586-023-03196-y

Why single-submission policies need to die (and what to do in the meantime).

Abstract

Vanillin is a popular and versatile flavor compound, almost entirely produced from petroleum-derived phenol by a multi-step chemical synthesis. The process is hazardous to the environment and unsustainable for its fossil oil usage. Therefore, developing environmentally friendly, efficient, and sustainable routes to biobased vanillin is essential. Here, we report on vanillin production from 4-n-propylguaiacol (4PG), one of the main components in lignin oil obtained through reductive catalytic fractionation (RCF) of soft wood, by employing recombinant Escherichia coli cells. Conversion is based on the expression of two engineered oxidative enzymes: a 4-n-propylguaiacol oxidase and an isoeugenol dioxygenase. A high yield of vanillin, 66% from 4PG in RCF lignin oil was achieved through rounds of optimisation of the whole-cell conversion process. This high-performance strategy was readily scaled up to produce vanillin at an unprecedented 18% and 3% yield based on lignin oil and spruce wood respectively. The whole-cell bioconversion process shows good tolerance even at high loadings of starting material, showcasing the robustness and applicability of the employed biocatalysts. This work paves the way for further development towards the efficient production of high-titer biobased vanillin using depolymerised lignin as the feedstock.

The FeCo−FeO interfaces derived from ZIF-67 exhibit excellent catalytic performance for the hydrogenation of methyl levulinate to 1,4-pentanediol.

Abstract

In this work, a series of N-doped carbon supported FeCo bimetallic catalysts with plentiful FeCo alloy-FeO interfaces, which are derived from metal-organic frameworks (MOFs) ZIF-67, are designed for the one-pot direct conversion of methyl levulinate to 1,4-pentanediol. The FeCo alloy-FeO interfaces are precisely controlled via tuning the reduction temperatures and Fe/Co ratios. The optimal catalyst gives a high 1,4-pentanediol yield of 90.5 % along with complete conversion of methyl levulinate. These catalysts are carefully characterized by multiple techniques, such as HRTEM, XRD, XPS, NH₃−TPD, and Py−IR. It is found that Co presents in electron deficiency caused by the electron transference from Co to Fe in FeCo alloy, which in turn enhances the heterolysis of H₂. In addition, plentiful Lewis acid sites derived from interfacial FeO species favour the re-adsorption and the ring-opening reaction of γ-valerolactone. With the synergy between FeCo alloy and Lewis acid, the FeCo alloy-FeO interfaces exhibit excellent catalytic activity for selective hydrogenation of methyl levulinate to 1,4-pentanediol.

A general and robust nitrogen-doped carbon supported Fe single-atom catalyst exhibits highly selective C−C/C=C bond cleavage reactivity in the presence of air (O₂) and water (H₂O) under comparably mild conditions. The present atomically dispersed Fe−N sites can efficiently activate O₂ and H₂O to generate singlet ¹O₂ and hydroxide species, which take part selectively in the C−C bond cleavage and lead to a significant promotion in activity.

Abstract

The development of methods for selective cleavage reactions of thermodynamically stable C−C/C=C bonds in a green manner is a challenging research field which is largely unexplored. Herein, we present a heterogeneous Fe−N−C catalyst with highly dispersed iron centers that allows for the oxidative C−C/C=C bond cleavage of amines, secondary alcohols, ketones, and olefins in the presence of air (O₂) and water (H₂O). Mechanistic studies reveal the presence of water to be essential for the performance of the Fe−N−C system, boosting the product yield from <1 % to >90 %. Combined spectroscopic characterizations and control experiments suggest the singlet ¹O₂ and hydroxide species generated from O₂ and H₂O, respectively, take selectively part in the C−C bond cleavage. The broad applicability (>40 examples) even for complex drugs as well as high activity, selectivity, and durability under comparably mild conditions highlight this unique catalytic system.

Nature, Published online: 06 September 2023; doi:10.1038/d41586-023-02757-5

The fossil is as old as the ‘first bird’, Archaeopteryx, and might have specialized in running or wading instead of flying.

Microwave-assisted batch and flow syntheses of pyrrolidones from levulinic acid have been exploited under neat conditions and using CPME as green solvent.

Abstract

This paper reports a new sustainable protocol for the microwave-assisted catalytic conversion of levulinic acid into N-substituted pyrrolidones over tailor-made mono (Pd, Au) or bimetallic (PdAu) catalysts supported on either highly mesoporous silica (HMS) or titania-doped HMS, exploiting the advantages of dielectric heating. MW-assisted reductive aminations of levulinic acid with several amines were first optimized in batch mode under hydrogen pressure (5 bar) in solvent-free conditions. Good-to-excellent yields were recorded at 150 °C in 90 min over the PdTiHMS and PdAuTiHMS, that proved recyclable and almost completely stable after six reaction cycles. Aiming to scale-up this protocol, a MW-assisted flow reactor was used in combination with different green solvents. Cyclopentyl methyl ether (CPME) provided a 99 % yield of N-(4-methoxyphenyl) pyrrolidin-2-one at 150 °C over PdTiHMS. The described MW-assisted flow synthesis proves to be a safe procedure suitable for further industrial applications, while averting the use of toxic organic solvents.

Catalytic conversion of Biomass-derived Levulinic Acid! This review attempts to showcase an efficient catalytic system of levulinic acid reductive amination into pyrrolidones with core concerns on catalyst design and conditional optimization.

Abstract

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

Nature, Published online: 15 August 2023; doi:10.1038/d41586-023-02573-x

The right configuration of pacers could lead to the fastest marathon ever run.

Incorporating deuteriums into the correct positions of organocatalysts increases their stability and robustness, just like the story of “The Three Little Pigs”: the first two pigs hastily construct houses made of straw and sticks (non-deuterated and dideuterated catalysts), but they were quickly destroyed by the wolf′s huffing and puffing (OH⁻). In contrast, the third pig took time to build a sturdy house made of bricks (tetradeuterated catalyst), and the brick house remained intact. More information can be found in the Research Article by Y. Liu, H. Naka, K. Maruoka and co-workers. (DOI: 10.1002/chem.202301866).

This review covers examples where C−H activation has been implemented on a preparative synthetic scale for the synthesis of drugs/drug candidates. Key features of the optimization process, challenges and potential of such methods in the pharmaceutical industry are discussed for various metals and transformations.

Abstract

C−H activation is an attractive methodology to increase molecular complexity without requiring substrate prefunctionalization. In contrast to well-established cross-coupling methods, C−H activation is less explored on large scales and its use in the production of pharmaceuticals faces substantial hurdles. However, the inherent advantages, such as shorter synthetic routes and simpler starting materials, motivate medicinal chemists and process chemists to overcome these challenges, and exploit C−H activation steps for the synthesis of pharmaceutically relevant compounds. In this review, we will cover examples of drugs/drug candidates where C−H activation has been implemented on a preparative synthetic scale (range between 355 mg and 130 kg). The optimization processes will be described, and each example will be examined in terms of its advantages and disadvantages, providing the reader with an in-depth understanding of the challenges and potential of C−H activation methodologies in the production of pharmaceuticals.