Jonas Wuyts

Synlett
DOI: 10.1055/a-2007-2958

A highly efficient, practical, and ligand-free palladium-catalyzed carbonylation of aryl iodides with alkenylboronic acids has been developed. A variety of chalcones and α-branched enones were isolated in satisfactory to good yields with good substrate compatibilities under an ambient pressure of CO at room temperature. Moreover, the transformation proceeds well in the presence of a substoichiometric amount of base. The merit of this strategy as a late-stage functionalization platform has been demonstrated by modifications of complex substrates derived from estrone and 3-phenyl-l-alanine.
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Article in Thieme eJournals:
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This review presents the properties of graphdiyne (GDY), the recent progress in the development of GDY-based atomic catalysts (ACs), especially their applications in energy conversion, and reveals the relationship between the coordination engineering of GDY-based ACs and their catalytic performance. Future challenges and opportunities are also discussed.

Abstract

As a special carbon material, graphdiyne (GDY) features the superiorities of incomplete charge transfer effect on the atomic level, tunable electronic structure and anchoring metal atoms directly with organometallic coordination bonds M (metal)-C (alkynyl carbon in GDY), providing it an ideal platform to construct single-atom catalysts (ACs). The coordination environment of single atoms anchored on GDY plays a key role in their catalytic performance. The mini-review highlights state-of-the-art progress in the rational design of GDY-based ACs and their applications, and mainly reveals the relationship between the coordination engineering of the GDY-based ACs and corresponding catalytic performance. Finally, some prospects concerning the future development of GDY-based ACs in energy conversion are also discussed.

A 4-enzyme cell-free system transforms vinyl esters into β-hydroxy acids in the absence of ATP and ancillary electron donors through concurrent abiotic thiolysis, non-decarboxylating Claisen condensation, ketone reduction and hydrolysis steps. The same substrate provides the energy to activate the acyl group and the redox power to reduce the condensed ketone.

Abstract

In vitro biosynthetic pathways that condense and reduce molecules through coenzyme A (CoASH) activation demand energy and redox power in the form of ATP and NAD(P)H, respectively. These coenzymes must be orthogonally recycled by ancillary reactions that consume chemicals, electricity, or light, impacting the atom economy and/or the energy consumption of the biosystem. In this work, we have exploited vinyl esters as dual acyl and electron donor substrates to synthesize β-hydroxy acids through a non-decarboxylating Claisen condensation, reduction and hydrolysis stepwise cascade, including a NADH recycling step, catalyzed by a total of 4 enzymes. Herein, the chemical energy to activate the acyl group with CoASH and the redox power for the reduction are embedded into the vinyl esters. Upon optimization, this self-sustaining cascade reached a titer of (S)-3-hydroxy butyrate of 24 mM without requiring ATP and simultaneously recycling CoASH and NADH. This work illustrates the potential of in vitro biocatalysis to transform simple molecules into multi-functional ones.

Nature, Published online: 25 January 2023; doi:10.1038/s41586-022-05639-4

Polymeric ionic liquids for conversion of cellulose into levulinic acid: A high levulinic acid yield of 79.4 % was achieved when used cellulose as substrates and sulphonic acid-functionalized polymeric ionic liquids as catalyst.

Abstract

Sulphonic acid-functionalized polymeric ionic liquids (PILs) were synthesized and applied into catalytic conversion of cellulose into levulinic acid (LA). The structure, thermal stability, and Hammett acidity function (H₀) of PILs were characterized and all were more thermostable than those of small-molecular ionic liquids (IL). At the optimum reaction conditions, the LA yield was maximized to 79.4 % by catalyst [Pim]CH₃SO₃. More importantly, catalyst [Pim]CH₃SO₃ performed well in other biomass conversion, such as cellobiose, starch and rice husk. The product LA can be easily extracted by methyl isobutyl ketone from the reaction mixture. The PILs with high catalytic activity were easily recycled with an LA yield up to 68.9 % even after five cycles. These sufficient PILs will offer new approaches for transforming biomass to platform chemicals.

Alkylation with alcohols: Herein, nickel-catalyzed hydrogen borrowing strategy was employed for alkylation of 2-oxindoles using alkyl alcohols. Initial mechanistic studies, deuterium labelling experiments and late stage synthetic modulation of the alkylated products were performed.

Abstract

Herein, a simple and efficient nickel-catalyzed C-3-selective alkylation of 2-oxindoles using primary alkyl and allylic alcohols have been demonstrated. The catalytic protocol enables transformations in the presence of free hydroxyl group, amine, cycloalkanes, olefins, and lactam including more challenging C2-C4 alcohols, citronellol and oleic acid derived alcohol in up to 96 % yield. Initial mechanistic studies and deuterium labelling experiments were performed. Synthetic modulations of the lactam enabled new routes for the synthesis of C-3-substituted indoles, indolines, and un-symmetric urea derivatives.

Ethanol is used as a hydrogen source and an alkylating agent in the Ir-catalyzed transfer hydrogenation and alkylation of ketones and aldehydes with amides as simple ligands affording alcohols in good to excellent yields. Our studies revealed the significant role of the base in achieving the TH and alkylation of carbonyl compounds with ethanol. The control experiments indicated the formation of Ir−H species and the important role of ligand in stabilizing the metal complex.

Abstract

Bio-derived ethanol is a promising green and sustainable hydrogen-donor solvent. Herein, we have developed Ir-catalyzed transfer hydrogenation of ketones and aldehydes using ethanol as a hydrogen source with amides as simple ligands. Furthermore, the alkylation of ketones and tandem alkylation/transfer hydrogenation of acetophenones is reported with ethanol.

Nature Catalysis, Published online: 16 December 2022; doi:10.1038/s41929-022-00905-0

Glycerol dehydration using metal oxides: This critical review discusses different aspects about glycerol dehydration to acetol and acrolein, emphasizing surface reactions and the participation of active sites as well as deactivation mechanisms from metal oxide which are fundamental for the design of new catalysts and can enkindle ideas for the development of solids resistant to deactivation by coke and sintering.

Abstract

Glycerol dehydration to acetol and acrolein is an interesting reaction pathway for conversion of biomass-derived products. However, they undergo extensive deactivation due to coke deposition and sintering, requiring the design of stable catalysts. The oxides stand out due to their natural abundance, simple synthesis, low cost and tunable acidic, basic and redox properties. The different studies apply these oxides as pure phase, supported, mixed or doped. However, it is observed that despite the large number of applied oxides in glycerol conversion, few works describe in detail about more complex oxides such as ferrites, hexaferrites, perovskites, among others. This review reports different acid oxides in the glycerol dehydration to acetol and acrolein as well as basic and redox oxides, describing a historical perspective, showing the most important theoretical foundations of heterogeneous catalysis to comprehend surface reactions and mentioning the different possibilities to understanding the different reactional pathway, highlighting the proposal mechanisms that explain the participation of the different active sites on the surface reactions. Furthermore, the sequence of reactions which show the origin of the coke deposited on catalyst surface was presented, emphasizing the main challenges. The role of the Lewis and Brønsted acid-base sites present in the metal oxides and their interactions on glycerol dehydration were described, providing a direction to design catalysts for selective dehydration reactions resistant against coke deposition and sintering.

Waste to fuel: Artificial cell-free enzyme cascade allows the synthesis of the common biofuel ethanol and next-gen biofuel isobutanol from methanol and the second most abundant sugar in nature, xylose in one pot.

Abstract

In the face of increasing mobility and energy demand, as well as the mitigation of climate change, the development of sustainable and environmentally friendly alternatives to fossil fuels will be one of the most important tasks facing humankind in the coming years. In order to initiate the transition from a petroleum-based economy to a new, greener future, biofuels and synthetic fuels have great potential as they can be adapted to already common processes. Thereby, especially synthetic fuels from CO₂ and renewable energies are seen as the next big step for a sustainable and ecological life. In our study, we directly address the sustainable production of the most common biofuel, ethanol, and the highly interesting next-generation biofuel, isobutanol, from methanol and xylose, which are directly derivable from CO₂ and lignocellulosic waste streams, respectively, such integrating synthetic fuel and biofuel production. After enzyme and reaction optimization, we succeeded in producing either 3 g L⁻¹ ethanol or 2 g L⁻¹ isobutanol from 7.5 g L⁻¹ xylose and 1.6 g L⁻¹ methanol. In our cell-free enzyme system, C1-compounds are efficiently combined and fixed by the key enzyme transketolase and converted to the intermediate pyruvate. This opens the way for a hybrid production of biofuels, platform chemicals and fine chemicals from CO₂ and lignocellulosic waste streams as alternative to conventional routes depending solely either on CO₂ or sugars.