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[Display omitted] Photoelectrochemical (PEC) organic transformation at the anode coupled with cathodic H 2 generation is a potentially rewarding strategy for efficient solar energy utilization. Nevertheless, achieving the full conversion of organic substrates with exceptional product selectivity remains a formidable hurdle in the context of heterogeneous catalysis at the solid/liquid interface. Here, we put forward a quasi-homogeneous catalysis concept by using the reactive oxygen species (ROS), such as ·OH, H 2 O 2 and SO 4 •− , as a charge transfer mediator instead of direct heterogeneous catalysis at the solid/liquid interface. In the context of glycerol oxidation, all ROS exhibited a preference for first-order reaction kinetics. These ROS, however, showcased distinct oxidation mechanisms, offering a range of advantages such as ∼ 100 % conversion ratios and the flexibility to tune the resulting products. Glycerol oxidative formic acid with Faradaic efficiency (FE) of 81.2 % was realized by the H 2 O 2 and ·OH, while SO 4 •− was preferably for glycerol conversion to C 3 products like glyceraldehyde and dihydroxyacetone with a total FE of about 80 %. Strikingly, the oxidative coupling of methane to ethanol was successfully achieved in our quasi-homogeneous system, yielding a remarkable production rate of 12.27 μmol h−1 and an impressive selectivity of 92.7 %. This study is anticipated to pave the way for novel approaches in steering solar-driven organic conversions by manipulating ROS to attain desired products and conversion ratios. [ABSTRACT FROM AUTHOR]

The synthetic potential of substituted 1,4‐dioxenes is well recognised, although the chemistry of 2‐aryl‐1,4‐dioxenes is relatively unexplored. Their transition metal‐catalysed synthesis has been limited to Stille‐type cross‐coupling chemistry, typically showing long reaction times, or proceeding at high reaction temperatures. Here we present a facile and general methodology for the cross‐coupling of aryl bromides with lithium 1,4‐dioxene, affording a range of 2‐aryl‐1,4‐dioxenes in generally good yields. We highlight the synthetic applicability of this transformation at multigram scale, and demonstrate the versatility of the products by conversion of the dioxene units to various carbonyl‐based functionalities. Additionally, we present a concise two‐step synthesis of an arylated analogue to a known 1,4‐dioxene‐based antifungal agent. [ABSTRACT FROM AUTHOR]

In this study, we present the successful application of new and known stable 16‐electron ruthenium(II) pincer complexes POCOP, based on the naphthoresorcinate backbone, [Ru(X)(POCOP)(CO)] (X = H, Cl, Br, I, OCOCF3), in the catalytic alkylation of ketones and the coupling between amines and primary alcohols under mild conditions. These protocols demonstrated tolerance to a wide range of alcohols, ketones, and anilines, with reactions proceeding in high conversions and selectivity towards the hydrogenated ketones and the imines. The use of an excess of alcohol as the proton source facilitated the formation of the hydrogenated products. These results mark a significant advancement in the development of catalytic reactions with ruthenium POCOP pincer derivatives. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Converting CO2 into valuable chemicals is an effective means to alleviate environmental pressure and the depletion of oil resources. Among them, polymers derived from the copolymerization of PO and CO2 have been widely studied because of their excellent properties. To meet the expansion of the application range of CO2‐based polymers, regulation of the CU in the polymer is imperative. Based on the understanding of the relationship between catalyst synergy and structure, we designed a new generation of polyester‐based polymeric catalysts APEPC‐R and RPEPC‐N with discretely distributed active centers to achieve the synthesis of CO2‐based polymers with regulated CU (from 50% to 90%). The discrete arrangement of catalyst active centers was demonstrated by 1H NMR and UV‐vis characterization. Benefiting from multi‐site synergy, high molecular weight (Mn > 100 kg/mol) CO2‐based copolymers with CU among 50%—90% were successfully synthesized and their properties were firstly investigated. This work not only contributes to enriching the scope of the application of CO2‐based copolymers but also provides a new platform for the development of a new generation of catalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Converting CO2 into valuable chemicals is an effective means to alleviate environmental pressure and the depletion of oil resources. Among them, polymers derived from the copolymerization of PO and CO2 have been widely studied because of their excellent properties. To meet the expansion of the application range of CO2‐based polymers, regulation of the CU in the polymer is imperative. Based on the understanding of the relationship between catalyst synergy and structure, we designed a new generation of polyester‐based polymeric catalysts APEPC‐R and RPEPC‐N with discretely distributed active centers to achieve the synthesis of CO2‐based polymers with regulated CU (from 50% to 90%). The discrete arrangement of catalyst active centers was demonstrated by 1H NMR and UV‐vis characterization. Benefiting from multi‐site synergy, high molecular weight (Mn > 100 kg/mol) CO2‐based copolymers with CU among 50%—90% were successfully synthesized and their properties were firstly investigated. This work not only contributes to enriching the scope of the application of CO2‐based copolymers but also provides a new platform for the development of a new generation of catalysts. [ABSTRACT FROM AUTHOR]

AbstractThe present work reports the green catalytic activity of homogeneous Schiff base common and mixed ligand CuII complexes for the synthesis of cyclic carbonates by cycloaddition of CO2 to oxiranes under optimized reaction conditions to get the TON of 1.98 × 104. Both selectivity and conversion of cyclic carbonate were 99% achieved at 100 °C, 1 atmospheric pressure of CO2, and a TBAB co-catalyst, in 12 h without solvent. [Cu(L1)2(H2O)2]·2H2O (1), [Cu(L2)2(H2O)2]·2H2O (2), and [Cu(L1L3)]·3H2O (3) were used as catalysts; [Cu(L1L3)]·3H2O (3) showed promising results for CO2 fixation to oxiranes for the production of cyclic carbonates, supposedly due to mixed ligands and square planar geometry of the complex. All three complexes were synthesized in 5 h by the conventional method using methanol and characterized by NMR, FT–IR, ESI mass, UV-visible, ESR, , TGA, microelemental analysis, and magnetic susceptibility. The FT–IR and 1H NMR spectroscopic data suggest bidentate coordinating ligand via ON donors. The electronic transitions observed were 2B1g→2A1g (ν1),2B1g→2B2g (ν2), and 2B1g→2Eg (ν3), attributed to the tetragonally elongated octahedral geometry (distorted octahedral) around CuII for 1 and 2, while 2B1g→2B2g (ν1), 2B1g→2A1g (ν2), and 2B1g→2Eg (ν3), from the square planar geometry around CuII for 3, supported by g values from ESR graphs, thermogravimetric weight loss of lattice and coordinated water molecules. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) are an emerging class of materials, leveraging maximum atom utilization and distinctive structural and electronic properties to bridge heterogeneous and homogeneous catalysis. Direct imaging methods, such as aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy, are commonly applied to confirm the atomic dispersion of active sites. However, interpretations of data from these techniques can be challenging due to simultaneous contributions to intensity from impurities introduced during synthesis processes, as well as any variation in position relative to the focal plane of the electron beam. To address this matter, this paper presents a comprehensive study on two representative SACs containing isolated nickel or copper atoms. Spectroscopic techniques, including X‐ray absorption spectroscopy, were employed to prove the high metal dispersion of the catalytic atoms. Employing scanning transmission electron microscopy imaging combined with single‐atom‐sensitive electron energy loss spectroscopy, we scrutinized thin specimens of the catalysts to provide an unambiguous chemical identification of the observed single‐atom species and thereby distinguish impurities from active sites at the single‐atom level. Overall, the study underscores the complexity of SACs characterization and establishes the importance of the use of spectroscopy in tandem with imaging at atomic resolution to fully and reliably characterize single‐atom catalysts. [ABSTRACT FROM AUTHOR]

Since the milestone contribution by Chen and White in 2007, bioinspired non‐heme bis‐amino‐bis‐pyridylmethyl Fe complexes have been at the forefront of studies related to designing catalytic approaches for direct oxidative functionalization of aliphatic C−H bonds. This, however, has not developed into large‐scale synthetic applications to date. The present concept is aimed at briefly discussing the state‐of‐the‐art of non‐heme Fe catalyzed oxidations of organic molecules with H2O2, the current oxidant of choice of bioinspired oxidation catalysis, mostly focusing on C−H oxidations, and analyzing the peculiarities of their reactivity through the prism of potential applications in fine organic synthesis. [ABSTRACT FROM AUTHOR]

A custom‐made Raman setup is improved and adjusted to allow its use in Ex zones by using a 1‐mW laser and no optical focusing elements. The application under consideration is the hydroformylation of decene to undecanal, which must take place under explosion protection. To investigate the dispersive mixture, a separation takes place in a phase separation cell in which the Raman probe performs measurements. It can be shown that, with the use of highly sensitive detectors, even very low excitation powers can lead to a processable signal, and thus the application of Raman measurement technology far below the requirements of explosion protection is possible. [ABSTRACT FROM AUTHOR]

The anthracene‐appended Schiff base N1‐(anthracene‐9‐methylene)benzene‐1,2‐diamine and its Cu(II) complex has been synthesized and anchored on MCM‐41 support (MCM@CP@AnL@Cu 1). The synthesized catalyst was characterized by various analytical techniques including single crystal X‐ray. Malononitrile, 1,3‐dione, and aromatic aldehydes with various substituents were used in one‐pot, three‐component synthesis of 2‐amino‐3‐cyano‐4H‐pyran/chromene derivatives using above catalyst 1. All the products of the catalytic reaction were characterized by 1H and 13C NMR spectra. We have also proposed a probable reaction mechanism involved in the catalytic reaction. The present catalyst has several advantages like works in mild reaction conditions, that is, at 80 °C, gives higher yields up to 97%, has thermal stability up to 295 °C, and can be reused up to 5 cycles. The immobilized material did not show any considerable leaching or deterioration throughout the catalytic reactions, confirming that it possesses a practical benefit over homogeneous catalysis. The MCM@CP@AnL@Cu (1) is believed to be a good solid heterogeneous catalyst and meets the need of green chemistry for sustainable environment. To the best of our knowledge, this is first example of anthracene‐based Cu (II)‐Schiff base complexes immobilized on modified MCM‐41 surfaces for the multicomponent synthesis of 4H‐pyrans. [ABSTRACT FROM AUTHOR]

A palladium capsule, made of three cavitands, namely P,P-dichlorido{5,17-bis[5-(diphenylphosphanyl)-4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]arenyl-17-oxymthyl]-4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]arene}palladium(II) (1), was synthetized by coordination of the corresponding diphosphinated ligand and the palladium precursor [PdCl2(PhCN)2] in 27% yield. The obtained P,P-chelate complex was fully characterized by elemental analysis, NMR and mass spectrometry. Molecular dynamics simulations carried out on the metallo-capsule showed the structure made by the three cavitands was slightly distorted over the 1 μs of the simulation. The evaluation of the palladium capsule 1 in the reaction between arylacetylenes and Et3SiH in undried conditions unequivocally demonstrates a drastic change in chemoselectivity, with the formation of the partially hydrogenation product rather than the hydrosilylation products observed with complexes whose active center is more accessible, for instance [PdCl2(PPh3)2]. [ABSTRACT FROM AUTHOR]

This perspective discusses bibliography data that has been published since 2018 on the synthesis of oxazolidinones by reacting corresponding aziridines with CO2. The versatility and viability of various procedures have been analyzed by considering the variety of tested substrates as well as experimental conditions and catalytic systems used. Collected data highlights that the reaction can be effectively promoted by several homogeneous and heterogeneous catalytic systems that have been optimized in order to conjugate the process sustainability and productivity with convenient procedural costs. [ABSTRACT FROM AUTHOR]

ABSTRACT NHC pincers (NHC = N‐heterocyclic carbene), which combine the structural benefits of both carbenes and pincer platforms, have shown diverse applications, spanning from fundamental organometallic chemistry to homogeneous catalysis. Although aryl‐bridged bis(NHCs) represent the earliest developed and most studied type of NHC pincers, such [C^C^C]‐platforms have been underutilized in the synthesis of rhodium complexes. In this study, we present several less explored organorhodium(III) complexes featuring [C^C^C]‐pincers. Their synthetic route via a convenient oxidative addition approach has been explored, and the obtained cyclorhodium(III) complexes show versatile coordination geometry (square pyramidal or octahedral). Additionally, these cyclorhodium(III) complexes exhibit very different regioselectivity in catalytic alkyne hydrosilylations compared to known Rh(III) NHC catalytic systems. Finally, a few mechanistic studies have also been conducted, and a plausible mechanism was proposed. [ABSTRACT FROM AUTHOR]

Organometallic complexes, which include ligands such as carbon monoxide (CO), carbenes, alkyls, phenyls, p-bound alkynes, alkenes, cyclopentadienyls, and arenes, have been extensively utilized in fields like materials chemistry and catalysis. These complexes also offer opportunities for the development of new medications with unique modes of action. Specifically, we are interested in anticancer drugs that can enhance the effectiveness of platinum treatments, broaden their range of action, reduce adverse effects, and prevent resistance. The distinct physiochemical properties of organometallic complexes have made them valuable in homogeneous catalysis, including the production of lead compounds and therapeutic possibilities. Over the past 20 years, a small group of researchers worldwide has explored the medical applications of these compounds’ unique characteristics, such as their structural diversity, potential for ligand exchange, and redox and catalytic properties. The results have been remarkable, and it is anticipated that numerous other organometallic compounds will undergo clinical trials in the coming years in addition to those already underway. In this brief study, we outline the advantages that organometallic metal complexes have over coordination compounds and pure organic molecules. [ABSTRACT FROM AUTHOR]

The homolysis of chemical bonds represents one of the most fundamental reactivities of excited molecules. Historically, it has been exploited to generate radicals under ultraviolet (UV) light irradiation. However, unlike most contemporary radical‐generating mechanisms, the direct excitation to homolyze chemical bonds and produce aliphatic carbon‐centered radicals under visible light remains rare, especially in metallaphotoredox cross couplings. Herein, we present our design of the dihydropyrimidoquinolinone (DHPQ) reagents derived from ketones, which can undergo formal deacylation and homolytic C−C bond cleavage to release alkyl radicals without external photocatalysts. Spectroscopic and computational analysis reveal unique optical and structural features of DHPQs, rationalizing their faster kinetics in alkyl radical generation than a structurally similar but visible‐light transparent radical precursor. Such a capability allows DHPQ to facilitate a wide range of Ni‐metallaphotoredox cross couplings with aryl, alkynyl and acyl halides. Other catalytic and non‐catalyzed alkylative transformations of DHPQs are also feasible with various radical acceptors. We believe this work would be of broad interest, aiding the synthetic planning with simplified operation and expanding the synthetic reach of photocatalyst‐free approaches in cutting‐edge research. [ABSTRACT FROM AUTHOR]

Transition metal ions and their complexes play a crucial role in homogeneous catalysis. These catalysts are pivotal for the production of, for example, fine chemicals and pharmaceuticals. Nevertheless, because of the homogeneous nature of these catalysts, their extraction and removal from the crude reaction mixture is cumbersome. Here, we propose an alternative approach where metal‐based homogeneous catalysts are generated electrochemically from a metallic anode (Cu), followed by their use without current, and finally again electrochemically deposited on the cathode. The generated Cu ions were used as catalysts in three different reactions of lauroyl peroxide: one ligand‐free (coupling with dienes), one without ligand but with a heteroatom containing substrate (coupling with toluidine and styrene) and one in the presence of 1,10‐phen as ligand (coupling with indazole). In the first two cases, performance of the electrochemically generated catalysts was similar to those reported in literature for classically prepared homogeneous catalysts, whereas in the last case a new reaction was observed. After reaction, the homogeneous copper catalyst could be efficiently removed electrochemically: 99% of the copper could be removed for the ligand‐free reaction, 97% for the amine coupling, whereas 89% of copper could be removed for the reaction containing N‐heterocycle and 1,10‐phenanthroline. [ABSTRACT FROM AUTHOR]

The catalytic hydrogenation of CO2 to formate was achieved using the previously reported dichloro(η6‐p‐cymene){diphenyl(3‐methyl‐2‐indolyl)phosphine}ruthenium (1) as a catalyst under mild conditions. In this complex, the phosphorus‐based ligand adopts a κ1‐P coordination mode. The catalytic activity was achieved in the presence of DBU as a base providing a TONmax value of 3,800. In order to explore potential transformations occurring within the catalytic reactions, a series of stoichiometric tests were performed. Complex 1 was reacted with DBU to form chloro(η6‐p‐cymene){diphenyl(3‐methyl‐2‐indolide)phosphine}ruthenium (2). Structural characterization of complex 2 confirmed a κ2‐P,N coordination mode for the ligand resulting in a four membered metallacycle. Reaction of 2 with H2 led to the formation of hydrochloro(η6‐p‐cymene){diphenyl(3‐methyl‐indolyl)phosphine}ruthenium (3), albeit not with a clean conversion. This is the product resulting from the formal addition of hydrogen across the Ru−N bond of the metallacycle. Complex 3 was also synthesized via an alternative route involving the reaction of complex 1 with Me2NH • BH3 as a means of converting Ru−Cl to Ru−H [ABSTRACT FROM AUTHOR]

The selective, transition metal‐free hydrosilylation of CO2 to CH2(OSiEt3)2 has been achieved under mild conditions and in high isolated yields (up to 90%) by using Et3SiH and the simple, easily prepared borohydride catalyst Li+[HB(C6F5)3]−. The resulting CO2‐derived bis(silyl)acetal product—whose mechanism of formation has been interrogated through detailed computational and experimental studies—can be rapidly valorized through the facile synthesis of N‐heterocyclic carbenes, via their corresponding imidazolium salts. By using relatively inexpensive, isotopically enriched 13CO2 this protocol can be exploited to prepare NHC isotopologues that are selectively 13C labelled at the key, ligating C2 position. This provides an electronically responsive 13C NMR spectroscopic handle with dramatically enhanced sensitivity, which can directly benefit reactivity studies in both organo‐ and organometallic catalysis, where NHC use is ubiquitous. [ABSTRACT FROM AUTHOR]

ABSTRACT Silylene metal complexes exhibit excellent catalytic activity and selectivity in homogeneous catalysis. However, there are relatively few examples of silylene metal complexes as catalysts for the hydrosilylation of alkenes. In order to study the effect of a silylene ligand on the catalytic performance of [PSiP] pincer Co(II) chloride for alkene hydrosilylation, the PMe3 ligand in (MeSi(C6H4‐PPh2)2)Co (PMe3)Cl (1) was replaced by a silylene ligand, and a silylene [PSiP] pincer Co(II) chloride, (MeSi(C6H4‐PPh2)2)Co (PhC (NtBu)2Si)Cl (2), was used as catalyst to study its catalytic activity in alkene hydrosilylation. It was confirmed that silylene Complex 2 has excellent catalytic activity for alkene hydrosilylation with Ph2SiH2 as a hydrogen source. For alkene hydrosilylation, compared to phosphine Complex 1, silylene Complex 2 does not need NaBHEt3 as an additive. In addition, for aromatic alkenes, silylene Complex 2 has anti‐Markovnikov selectivity, while phosphine Complex 1 provides Markovnikov products in the presence of NaBHEt3. [ABSTRACT FROM AUTHOR]

Knölker complexes have been recently used to perform the catalytic C1‐oxidation of unprotected sugars into sugar lactones. This oxidation method remained limited by the stability of the catalyst with the polyhydroxylated substrates. Our objective is now to overcome these limitations and extend this method to more challenging substrates such as disaccharides. We proposed in this paper two original designs of Knölker‐type complexes conceived to promote secondary H‐bond interactions with the OH groups of the substrates to stabilise the system and favour the transformation. In total, 8 novel pre‐catalysts were synthesised, fully characterised and applied in the anomeric oxidation of several sugar derivatives. Two of these new complexes proved to be more efficient than the Knölker complex for the oxidation of disaccharides. Moreover, a preliminary DFT study revealed the presence of H‐bonds interactions between the substrate and the oxygen atom on the ligand arm of the best complexes suggesting a beneficial role of this heteroatom on the catalytic efficiency. [ABSTRACT FROM AUTHOR]

Site‐selective C−H bond functionalization of arenes at the para position remains extremely challenging primarily due to its relative inaccessibility from the catalytic site. As a consequence, it is significantly restricted to limited molecular scaffolds. Herein, we report a method for the para‐C−H borylation of aromatic aldimines and benzylamines using commercially available ligands under iridium catalysis. The established method displays excellent para selectivity for variously substituted aromatic aldimines, benzylamines and bioactive molecules. Based on several control experiments, it is proposed that a Lewis acid−base interaction between the nitrogen and boron functionality guides the para selectivity via a steric shield for the aromatic aldimines, where Bpin acts as a transient directing group. However, the steric shield of the in situ generated N−Bpin moiety controlled the overall selectivity for the para borylation of benzylamines. [ABSTRACT FROM AUTHOR]

Catalysis plays a crucial role in advancing sustainability. The unique reactivity of frustrated Lewis pairs (FLPs) is driving an ever-growing interest in the transition metal-free transformation of small molecules like CO2 into valuable products. In this area, there is a recent growing incentive to heterogenize molecular FLPs into porous solids, merging the benefits of homogeneous and heterogeneous catalysis – high activity, selectivity, and recyclability. Despite the progress, challenges remain in preventing deactivation, poisoning, and simplifying catalyst-product separation. This review explores the expanding field of FLPs in catalysis, covering existing molecular FLPs for CO2 hydrogenation and recent efforts to design heterogeneous porous systems from both experimental and theoretical perspectives. Section 2 discusses experimental examples of CO2 hydrogenation by molecular FLPs, starting with stoichiometric reactions and advancing to catalytic ones. It then examines attempts to immobilize FLPs in porous matrices, including siliceous solids, metal–organic frameworks (MOFs), covalent organic frameworks, and disordered polymers, highlighting current limitations and challenges. Section 3 then reviews computational studies on the mechanistic details of CO2 hydrogenation, focusing on H2 splitting and hydride/proton transfer steps, summarizing efforts to establish structure–activity relationships. It also covers the computational aspects on grafting FLPs inside MOFs. Finally, Section 4 summarizes the main design principles established so far, while addressing the complexities of translating computational approaches into the experimental realm, particularly in heterogeneous systems. This section underscores the need to strengthen the dialogue between theoretical and experimental approaches in this field. [ABSTRACT FROM AUTHOR]

Context: The field of chemistry has significantly evolved, with catalysis playing a crucial role in transforming chemical processes. From Valerius' use of sulfuric acid in the sixteenth century to modern advancements, catalysis has driven innovations across various industries. The introduction of gold as a catalyst marked a pivotal shift, expanding its applications beyond ornamentation to homogeneous catalysis. Gold's unique properties, such as its electrophilic nature and flexibility, have enabled its use in synthesizing complex molecules, including those in nanomedicine and sustainable chemical processes. The development of gold-based complexes, particularly in hydroalkoxylation and hydroamination reactions, showcases their efficiency in forming carbon–oxygen bonds under mild conditions. Recent studies on dual gold catalysis and heterobimetallic complexes further highlight gold's versatility in achieving high turnover rates and selectivity. This evolution underscores the potential of gold catalysis in advancing environmentally sustainable methodologies and enhancing the scope of modern synthetic chemistry. The debate about the nature of monogold and dual-gold catalysis is open. Methods: DFT calculations have played a key role in promoting the activation of alkynes, in particular the hydrophenoxylation of alkynes by metal-based catalysts. They not only help identify the most efficient and selective catalysts but also aid in screening for those capable of performing a dual metal catalytic mechanism. The most commonly used functionals are BP86 and B3LYP, with the SVP and 6-31G(d) basis sets employed for geometry optimizations, and M06 with TZVP or 6-311G(d,p) basis sets used for single-point energy calculations in a solvent. Grimme dispersion correction has been explicitly added either in the solvent single point energy calculations or in the gas phase geometry optimizations or in both. To point out that M06 implicitly includes part of this dispersion scheme. [ABSTRACT FROM AUTHOR]

The development of palladium‐catalyzed fluorination with biaryl monophosphine ligands has faced two important problems that limit its application for bromoarenes: the formation of regioisomers and insufficient catalysis for heteroaryl substrates as bromothiophene derivatives. Overcoming these problems requires more ligand design. In this work, reliable theoretical calculations were used to elucidate important ligand features necessary for achieving more rate acceleration and selectivity. These features include increasing the ligand‐substrate repulsion and creating a negative charge in the space around the fluoride ion bonded to the palladium. The investigated L5 ligand presents these features, and the calculations predict that this ligand completely suppresses the regioisomer formation in the difficult case of 4‐bromoanisole. In addition, the free energy barriers are decreased by 2–3 kcal mol−1 in comparison with the catalysis involving the AlPhos ligand. Thus, the present study points out a direction for new developments in palladium‐catalyzed fluorination. [ABSTRACT FROM AUTHOR]

Exploration of efficient molecular water oxidation catalysts for long-term application remains a key challenge for the conversion of renewable energy sources into fuels. Cuboidal {Co4O4} complexes keep attracting interest as molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs. However, the application of many cluster-based catalysts for the oxygen evolution reaction still requires new stabilization strategies. Drawing inspiration from the stabilizing effects of natural polymers, we introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} cubane oxo clusters as oxygen evolution catalysts. Polypyrrole is applied as an efficient p-type conducting polymer that promotes hole transfer during the oxygen evolution reaction, resulting in higher turnover frequency compared to the pristine {Co4O4} oxo cluster and heterogeneous Co-oxide benchmarks. The asymmetric coordination of {Co4O4} not only mitigates catalyst decomposition pathways, but also increases the catalytic efficiency by exposing a directed cofacial dihydroxide motif during catalysis. Cuboidal {Co4O4} complexes are attractive molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs, but their application requires stabilization strategies. Here, the authors introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} clusters. [ABSTRACT FROM AUTHOR]

A key challenge in synthetic chemistry is the selection of high‐performing ligands for cross‐coupling reactions. To address this challenge, this work presents a classification workflow to identify physicochemical descriptors that bin monophosphine ligands as active or inactive in Ni‐catalyzed Suzuki‐Miyaura coupling reactions. Using five previously published high‐throughput experimentation datasets for training, we found that a binary classifier using a phosphine's minimum buried volume and Boltzmann‐averaged minimum electrostatic potential is most effective at distinguishing high and low‐yielding ligands. Experimental validations are also presented. Using the two physicochemical descriptors from the binary classifier to represent the chemical space of monophosphine ligands leads to a more predictive guide for structure‐reactivity relationships compared with classic chemical space representations. [ABSTRACT FROM AUTHOR]

We report the synthesis of alkyl 1,2,6‐triaryl‐4‐arylaminopiperidine‐3‐ene‐3‐carboxylates in acceptable yields (42%–71%) and high trans‐diastereoselectivity (69:31 to 100:0) through a one‐pot multicomponent reaction of aromatic aldehydes, aromatic amines, and β‐ketoesters catalyzed by phosphomolybdic acid in methanol at room temperature. The structure and stereochemistry of tetrahydropyridines were confirmed by X‐ray crystallography. This protocol stands out for its operational simplicity, the use of an inexpensive and commercially available heteropolyacid catalyst, low catalyst loading, and purification via simple filtration, resulting in acceptable yields and high diastereoselectivity. [ABSTRACT FROM AUTHOR]

The new diiron(I) complexes [Fe2Cp2(μ‐CO){μ‐k3C,kN‐C(R1)C(R2)C(CN)NMe(R)}], 3 a–o (R=alkyl or 4‐C6H4OMe; R1=alkyl, aryl, ferrocenyl (Fc), thiophenyl, CO2Me or SiMe3; R2=H, Me or CO2Me) were synthesized in moderate to high yields from the thermal decarbonylation of the bis‐carbonyl precursors 2 a–o, and were structurally characterized by IR and NMR spectroscopy, and single crystal X‐ray diffraction in four cases. Electrochemical behavior of one complex was also investigated. Complexes 3 a–o comprise a highly functionalized, multisite amino‐(cyano)allylidene ligand, including metal coordination of a tertiary amine group. Selected complexes displayed negligible to moderate catalytic activity in CO2/propylene oxide coupling, working under ambient conditions. Additionally, they were investigated as catalysts for the conversion of benzaldehyde to the corresponding borate ester 6 a, using pinacolborane (HBpin) as the borylating agent. Most complexes achieved good conversions at room temperature with 1 % catalyst loading, and data highlight the significant influence of the multisite ligand substituents on the catalytic performance. Notably, complex 3 m (featuring R=4‐methoxyphenyl, R1=Fc, R2=H) displayed the highest activity and effectively catalyzed the hydroboration of various aldehydes and ketones. A plausible mechanistic cycle involves metal coordination of the carbonyl substrate, its activation being possibly facilitated by intramolecular interactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Key Scientists Electron‐rich alkynes, such as ynol and thioynol ethers, have proven to be versatile and appealing partners in catalytic cycloaddition reactions, and thus have raised considerable attentions owing to the practical application in the modular assembly of valuable carbo‐ and heterocycles. The past decades have witnessed inspiring advances in this emerging field, and an increasing number of related discoveries have been exploited. Divided into two main sections on the basis of substrate type, in each section this comprehensive review will initially summarize their synthetic preparations and subsequently examine their reactivity in every sort of catalytic cycloaddition with emphasis on the methodology development, aimed at providing an access to this burgeoning area and encouraging further innovations in the near future. For the cycloaddition of ynol ethers, in 2004, Kozmin et al. firstly developed a silver‐catalyzed [2 + 2] cycloaddition of siloxy alkynes with electron‐poor olefins. In 2012, Hiyama et al. realized a palladium‐catalyzed formal [4 + 2] annulation of alkynyl aryl ethers with internal alkynes. In the same year, Sun et al. discovered an efficient [6 + 2] cyclization between siloxy alkynes and 2‐(oxetan‐3‐yl)benzaldehydes by applying HNTf2 as catalyst. In 2017, Wender et al. first utilized vinylcyclopropanes (VCPs) as coupling partners in the [5 + 2] annulation of ynol ethers. In 2018 and 2020, Ye et al. reported zinc‐catalyzed formal [3 + 2] and [4 + 3] cycloaddition, respectively. For the cycloaddition of thioynol ethers, in 2004, Hilt et al. realized a [4 + 2] cycloaddition by employing the alkynyl sulfides and acyclic 1,3‐dienes. In 2006, a ruthenium‐catalyzed [2 + 2] cycloaddition of thioynol ethers with bicyclic alkenes was accomplished by Tam. In 2014, Sun et al. reported an elegant iridium‐catalyzed click reaction of thioalkynes with azides. [ABSTRACT FROM AUTHOR]

Hydroalkylation of alkynes is a powerful method for alkene synthesis. However, regioselectivity has been difficult to achieve in transformations of internal alkynes hindering applications in the synthesis of trisubstituted alkenes. To overcome these limitations, we explored using boryl groups as versatile directing groups that can control the regioselectivity of the hydroalkylation and subsequently be replaced in a cross‐coupling reaction. The result of our exploration is a nickel‐catalyzed hydroalkylation of alkynyl boronamides that provides access to a wide range of trisubstituted alkenes with high regio‐ and diastereoselectivity. The reaction can be accomplished with a variety of coupling partners, including primary and secondary alkyl iodides, α‐bromo esters, α‐chloro phthalimides, and α‐chloro boronic esters. Preliminary studies of the reaction mechanism provide evidence for the hydrometalation mechanism and the formation of alkyl radical intermediates. [ABSTRACT FROM AUTHOR]

Nitrogen oxides (NOx) are major environmental pollutants and to neutralize this long‐term environmental threat, new catalytic methods are needed. Although there are biological denitrification processes involving four different enzymatic reactions to convert nitrate (NO3−) into dinitrogen (N2), it is unfortunately difficult to apply in industry due to the complexity of the processes. In particular, nitrate is difficult to functionalize because of its chemical stability. Thus, there is no organometallic catalysis to convert nitrate into useful chemicals. Herein, we present a nickel pincer complex that is effective as a bifunctional catalyst to stepwise deoxygenate NO3− by carbonylation and further through C−N coupling. By using this nickel catalysis, nitrate salts can be selectively transformed into various oximes (>20 substrates) with excellent conversion (>90 %). Here, we demonstrate for the first time that the highly inert nitrate ion can be functionalized to produce useful chemicals by a new organonickel catalysis. Our results show that the NOx conversion and utilization (NCU) technology is a successful pathway for environmental restoration coupled with value‐added chemical generation. [ABSTRACT FROM AUTHOR]

The chemical synthesis of unnatural amino acids (UAA) is a key strategy for preparing designed peptides, including pharmaceutically active compounds. Alterations of existing amino acid residues such as dehydroalanine (Dha) are particularly important since selected positions can be addressed without the necessity of a complete de novo synthesis. The intriguing UAA 4,5‐dihydroxynorvaline (Dnv) is found in a variety of naturally occurring peptides and biologically active compounds. However, no method is currently available to modify an existing peptide with this residue. We report the use of flavin catalysts and visible light irradiation for this challenge, which serves as a versatile strategy for converting Dha into Dnv. Our study shows that excited flavins are competent hydrogen atom abstraction catalysts for ethers and acetals, which allows masked 1,2‐dihydroxyethylene functionalization from 2,2‐dimethyl‐1,3‐dioxolane. The masked diol was successfully coupled to Dha residues, and a series of Dnv‐containing products is reported. A mild and orthogonal protocol for deprotection of the acetal group was also identified, allowing free Dnv‐modified peptides to be obtained. This method provides a straightforward strategy for Dnv functionalization, which is envisioned to be crucial for accessing natural products and synthetic analogues with pharmaceutical activity. [ABSTRACT FROM AUTHOR]

Cross-coupling reactions, which occur in both homogeneous and heterogeneous catalysis, have emerged as versatile tools in organic transformations and have had a profound impact on medicinal chemistry and drug discovery. However, conventional homogeneous systems have limitations such as small-scale synthesis, poor recyclability, and the susceptibility of catalysts to degradation. In contrast, heterogeneous systems with immobilized catalytic active sites offer superior stability and recyclability, making them essential for industrial applications. Recent interest in solar-driven organic transformations, particularly carbon-carbon and carbon-heteroatom cross-coupling reactions, has stimulated extensive research efforts. Among many materials, covalent organic frameworks (COFs) have emerged as leading candidates for heterogeneous photocatalysis due to their high crystallinity, π-conjugated framework, narrow band structure, uniform porosity, and tunable functionality. This review comprehensively examines the advantages of COFs as heterogeneous photocatalysts for carbon-carbon coupling, carbon-heteroatom cross-coupling, and oxidative coupling of amines. It highlights their role in providing a green catalytic route to organic transformations and proposes strategies to enhance their photocatalytic efficiency. Finally, the review discusses the future trajectory of COF-based heterogeneous catalysts for various cross-coupling reactions under visible light irradiation, highlighting the novelty and driving force behind current progress in this burgeoning field. [ABSTRACT FROM AUTHOR]

The catalytic activity of low‐valent transition metals for the cyclotrimerization of nitriles has rarely been investigated to date. Here, we report on the cyclotrimerization of benzonitrile (PhCN) and its derivatives using catalytic systems composed of magnesium and bis(indolyl)TiCl2 (bis(indolyl)=di(3‐methylindol‐2‐yl)phenylmethane), Cp2TiCl2 (Cp=η5‐C5H5), (CGC)TiCl2 (CGC=Me2Si(Me4C5)(tBuN)), TiCl4(thf)2 (thf=tetrahydrofuran), Cp*TiCl3 (Cp*=η5‐Me5C5), or CpTiCl3, which can be expected to generate coordinatively unsaturated Ti(II) complexes as the catalytically active species. All the investigated catalytic systems were active for the cyclotrimerization of PhCN. Notably, even the simple catalytic precursor (TiCl4(thf)2) mediated the cyclotrimerization of PhCN as well as p‐ and m‐tolunitriles. Moreover, these reactions can be carried out on the gram scale and the cyclotrimerized products can be isolated via recrystallization of the reaction mixture from hot toluene. The findings of this study suggest that low‐valent titanium species have the potential to serve as catalysts for the cyclotrimerization of PhCN and its derivatives. During this study, we also found that 2,4,6‐tri(p‐tolyl)‐1,3,5‐triazine, which is obtained from the cyclotrimerization of p‐tolunitrile, exhibits fluorescent properties in both the solid state and in solution. [ABSTRACT FROM AUTHOR]

While iron‐catalyzed C(sp2)−C(sp3) cross‐couplings have been widely studied and developed in the last decade, alkyl‐alkyl cross‐coupling systems with iron remain underdeveloped despite the importance of C(sp3)−C(sp3) bonds in organic synthesis. A major challenge to the development of these reactions is the current lack of fundamental insight into ligand effects and organoiron intermediates that enable effective alkyl‐alkyl couplings. The current study addresses this longstanding limitation using a combination of 57Fe Mössbauer spectroscopy, SC‐XRD (single‐crystal X‐ray diffraction) and reactivity studies of alkyl‐alkyl coupling with iron‐Xantphos to define the in situ formed iron‐Xantphos intermediates in catalysis. Combined with detailed reactivity studies, the nature of the key mechanistic pathways in catalysis and ligands effects to achieve effective alkyl‐alkyl cross‐coupling over competing β‐H elimination pathways are probed. Overall, these foundational studies provide a platform for future bespoke ligand and pre‐catalyst design for alkyl‐alkyl cross‐coupling methods development with sustainable iron catalysis. [ABSTRACT FROM AUTHOR]

A series of zinc aryloxides, [Zn4(sal‐Me)8]⋅2.5(C7H8) (1), [Zn4(sal‐Me)8]⋅CH2Cl2 (2), [Zn4(μ3‐OR)2(sal‐R)6] (3) (for R=Me (0.51), Et (0.49)), [Zn4(μ3‐OMe)4(sal‐Me)4(HOMe)4] (4), [Zn(sal‐Me)2(py)2]⋅THF (5), {[Zn(sal‐Me)2(tmbpy)] ⋅ 2(C6H5CH3)}n (6), [Zn2(sal‐Me)2(THF)2Cl2] ⋅ 0.5(C6H5CH3) (7), and [Zn4(μ3‐OMe)2(sal‐Me)4Cl2] (8) (Hsal‐Me=methyl salicylate, py=pyridine, tmbpy=4,4′‐trimethylenedipyridine) were obtained that have different nuclearities and central core topologies and contain ligands of different basicity and coordination abilities. [ABSTRACT FROM AUTHOR]

Homogenous advanced oxidation processes (AOPs) based on transition metal catalysts toward the activation of H2O2 to hydroxyl radical (•OH) have been widely applied to organic pollutants removal, such as Fenton and Fenton-like processes. These transition metal catalysts mostly flocculate as the pH increases. It's worth noting that the formed transition metal flocs are complex heterogeneous aggregations with active substances, providing diverse reaction spaces and interfaces. However, it is a challenge to distinguish the roles of transition metal flocs in the organic pollutants removal from homogeneous catalytic reactions. Herein, we unveiled a pathway for the long-lasting removal of organic pollutants via Cr flocs adsorbed with •OH (HO•-Cr flocs) using a stepwise method. First, adsorbed •OH (•OHads) within the HO•-Cr flocs was proved to be the active site forming hydrogen bond (H-bond) and van der Waals force with organic pollutants. Then, the presence of switchable electron transfer between Cr and OH groups within the HO•-Cr flocs was revealed, contributing to the persistent existence of •OHads and consequently ensuring the long-lasting organics removal. Further, this removal pathway of organic pollutants was confirmed during the leather wastewater treatment. These findings will complement a different pathway for organic pollutants removal via transition metal flocs and extend the lifetime of homogeneous AOPs based on transition metal catalysts, providing significant implications for their design and optimization. [ABSTRACT FROM AUTHOR]

Alkyl levulinates (ALs) are strategic compounds for the development of sustainable energy transition. In this regard, the direct alcoholysis of fructose and inulin for the selective ethyl levulinate (EL) production was investigated with a One‐Factor‐At‐a‐Time (OFAT) approach employing diluted H2SO4 as catalyst to clarify the role of the main reaction parameters (substrate and acid loadings, temperature, reaction time). The OFAT investigation on fructose ethanolysis allowed to reach the EL yield of 91.5 mol%. The inulin ethanolysis was then optimized adopting the multivariate approach based on the Response Surface Methodology (RSM), which highlighted the interplay of the reaction parameters on the selective EL production. This allowed to identify the optimal conditions to reach the highest EL yield (up to 89.3 mol%) and also those which ensured the highest EL concentration, adopting a substrate loading (14 wt%) higher than the majority ones reported in the literature according to the high gravity approach, and the lowest diethyl ether (DEE) by‐product yield. The DEE formation is scarcely investigated in the literature, but it can negatively influence the alcoholysis process, thus it was considered in this work. Moreover, the humin solid residue was deeply characterized to envisage its possible applications, under a circular economy perspective. [ABSTRACT FROM AUTHOR]

A new hydroxo‐bridged ruthenium (II) complex [{Ru(η6‐p‐cymene)(iPr2P−O)}2(μ‐OH)]Cl (2) has fortuitously been isolated from the reaction between the known ruthenium(II) complex [RuCl2(η6‐p‐cymene)(iPr2P‐OH)] (1) in either CDCl3 or CHCl3 solutions in the presence of excess DBU (1,8‐diazabicyclo(5.4.0)undec‐7‐ene) at room temperature. Complex 2 is only formed under specific conditions as an orange‐colored air and moisture stable binuclear complex. It is formed via the deprotonation of the P−OH unit in [RuCl2(η6‐p‐cymene)(iPr2P‐OH)]. Complex 2 has been fully characterized by spectroscopic and analytical methods. Its structure was determined by single crystal X‐ray diffraction which reveals a boat‐shaped motif containing a bridging hydroxide unit which undergoes hydrogen bonding with a chloride counterion. Complex 2 was utilized as a catalyst for the hydrogenation of CO2 to formic acid salt using molecular hydrogen. The catalytic reactions were performed at 100 °C in THF in the presence of DBU as a base to isolate [DBU+H][OC(O)H] salt as the final product. Using catalyst loadings down to 0.01 mol%, it was possible to hydrogenate gaseous CO2 with TONs up to 9900. [ABSTRACT FROM AUTHOR]

Harnessing CO2 in conjunction with inexpensive reusable H2 for catalytic hydrogenation is a viable method for lowering the environmental impact of industrial operations while producing useful chemicals and fuels. To make the process more sustainable, particular emphasis was paid to the heterogeneous catalyst system in this regard. Intending to profit from both homogeneous and heterogeneous catalysis in real‐world circumstances for the CO2 hydrogenation reaction, heterogenized molecular catalysts are receiving a lot of attention among heterogeneous catalysts. This review is devoted to significant developments in single‐site heterogenized molecular catalysts for CO2 hydrogenation reactions. Attempting to illustrate the state‐of‐the‐art developments in this domain, the present work meticulously summarizes several recently reported heterogenized molecular catalysts for the CO2 hydrogenation process producing formic acid/formate, N‐formamide, and methanol. The fundamental structure–activity relationships and mechanistic understanding are given particular attention since they offer solid foundations for sensible catalyst architectural design. Important variables that influence catalytic activity are also emphasized, such as electron density, metal dispersion, porous nature, surface area, a robust backbone, and coordination environment of metal sites. Finally, a short assessment is given as potential directions for further research. [ABSTRACT FROM AUTHOR]

Microkinetic modeling is a computational tool that allows simulating the evolution of the concentration of catalytically relevant species with time, providing a description of the catalytic system closer to the experimental. Microkinetic models have been mainly applied in organometallic catalysis as a means for validating mechanistic proposals by comparing experimental and computed rates and concentrations at a given time. However, this tool becomes very useful when studying complicated reaction mechanisms, aiding in identifying the catalyst resting state, optimizing reaction conditions, or improving the catalyst design. In this Concept, we focus on these applications of microkinetic modeling through the discussion of some selected examples. In addition, we also point out some of the challenges and limitations we may face when building microkinetic models, which may explain why they are still underused. [ABSTRACT FROM AUTHOR]

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon‐supported single atom catalysts focused on nitrogen‐doped carbons, which, unlike classic carbon materials, have a fairly well‐defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting‐edge analytical methods. [ABSTRACT FROM AUTHOR]

The combination of metal‐based homogeneous and heterogeneous catalysts in the same reaction media is a powerful, yet relatively unexplored approach in organic chemistry. This strategy can address important limitations associated with purely homogeneous or heterogeneous catalysis such as the incompatibility of different catalytic species in solution, or the limited tunability of solid catalysts, respectively. Moreover, the facile reusability of the solid catalyst, contributes to increase the overall sustainability of the process. As a result, this semi‐heterogeneous multi‐catalytic approach has unlocked significant advances in organic chemistry, improving existing reactions and even enabling the discovery of novel transformations, exemplified by the formal alkane metathesis. This concept article aims to showcase the benefits of this strategy through the exploration of diverse relevant examples from the literature, hoping to spur research on new metal‐based homogeneous‐heterogeneous catalyst combinations that will result in reactivity challenging to achieve by conventional homogeneous or heterogeneous catalysis alone. [ABSTRACT FROM AUTHOR]

A new hydroxo‐bridged ruthenium (II) complex [{Ru(η6‐p‐cymene)(iPr2P−O)}2(μ‐OH)]Cl (2) has fortuitously been isolated from the reaction between the known ruthenium(II) complex [RuCl2(η6‐p‐cymene)(iPr2P‐OH)] (1) in either CDCl3 or CHCl3 solutions in the presence of excess DBU (1,8‐diazabicyclo(5.4.0)undec‐7‐ene) at room temperature. Complex 2 is only formed under specific conditions as an orange‐colored air and moisture stable binuclear complex. It is formed via the deprotonation of the P−OH unit in [RuCl2(η6‐p‐cymene)(iPr2P‐OH)]. Complex 2 has been fully characterized by spectroscopic and analytical methods. Its structure was determined by single crystal X‐ray diffraction which reveals a boat‐shaped motif containing a bridging hydroxide unit which undergoes hydrogen bonding with a chloride counterion. Complex 2 was utilized as a catalyst for the hydrogenation of CO2 to formic acid salt using molecular hydrogen. The catalytic reactions were performed at 100 °C in THF in the presence of DBU as a base to isolate [DBU+H][OC(O)H] salt as the final product. Using catalyst loadings down to 0.01 mol%, it was possible to hydrogenate gaseous CO2 with TONs up to 9900. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed radical‐based enantioconvergent reactions have become a powerful strategy to synthesize enantiopure compounds from racemic starting materials. However, existing methods primarily address precursors with central chirality, neglecting those with axial chirality. Herein, we describe the enantioconvergent reductive coupling of racemic allenes with aldehydes, facilitated by a photoredox, chromium, and cobalt triple catalysis system. This method selectively affords one product from sixteen possible regio‐ and stereoisomers. The protocol leverages CoIII−H mediated hydrogen atom transfer (MHAT) and Cr‐catalyzed radical‐polar crossover for efficient stereoablation of axial chirality and asymmetric addition, respectively. Supported by mechanistic insights from control experiments, deuterium labeling, and DFT calculations, our approach offers synthetic chemists a valuable tool for creating enantioenriched chiral homoallylic alcohols, promising to advance radical‐based strategies for synthesizing complex chiral molecules. [ABSTRACT FROM AUTHOR]

Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)pyridin-2-ylmethylimine and N-(3-(triethoxysilyl)propyl)picolinamide were synthesized, characterized, and used as pre-catalysts in the transfer hydrogenation of C=C bonds in fatty acid methyl esters. The active catalysts from the Co, Ni, and Pd complexes sequentially hydrogenate the C18:2 chains to C18:1, which is further converted to C18:0 in the FAMEs of both methyl linoleate and jatropha biodiesel. The hydrogenation process was kinetically controlled, and after 3 h it yielded a biodiesel sample that contained 25.83% C16:0, 12.52% C18:2, 41.54% C18:1, 14.47% C18:0 and 3.0% C18:2 isomers. The un-hydrogenated jatropha diesel, hydrogenated jatropha diesel, and a B20 blend of jatropha were tested for susceptibility to oxidation reactions using the Rancimat method and FTIR spectroscopy, and the partial hydrogenation had improved the induction period by 3 h. [ABSTRACT FROM AUTHOR]

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H2SO4 or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO3H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes. [ABSTRACT FROM AUTHOR]

The possibility of catalysis by VO2+, Cr3+, Cr2O72–, Mn2+, MnO4–, Fe3+, Co2+, Ni2+, Cu2+, Ce3+, BrO3–, or IO3– ions of oxalic acid oxidation reaction with ozone in strongly acidic aqueous solutions at pH 0.3–1.7 has been studied. The final product of the oxidation is carbon dioxide. The kinetic regularities of the reaction have been determined from the rates of ozone consumption and carbon dioxide release. Without a catalyst, oxalic acid does not interact with ozone. It has been found that Mn2+, MnO4– and Co2+ ions are effective catalysts, while the catalytic effect of VO2+, Cr3+, Cr2O72–, Fe3+, Ni2+, Cu2+, Ce3+, BrO3–, or IO3– is weak or does not manifest itself at all. The effects of acidity and concentrations of the catalyst in solution and ozone in the gas phase on the kinetics of the process have been studied. Kinetic schemes of catalytic reactions and leading intermediates are proposed. The data obtained will help in choosing the optimal conditions for the process of oxidative mineralization of oxalic acid under the action of ozone in strongly acidic media. [ABSTRACT FROM AUTHOR]

Using palladium hydrazone complex as a homogeneous catalyst for SMC, we synthesized a library of 15 variant 3‐arylcoumarins. In this context, we report a set of four coordinated palladium(II) hydrazone complexes 1 and 2 having the general formula [Pd(L)(Cl)(PPh3)] by reacting the precursor complex [PdCl2(PPh3)2] with the hydrazone ligands HL1 or HL2. Single crystal XRD and conventional spectroscopic techniques were employed to characterize both complexes. From the catalytic application point of view, the new complexes 1 and 2 were tested as homogeneous catalysts towards the conversion of 3‐chlorocoumarins into 3‐arylcoumarins by activating the challenging CCl functionality. A minimal catalyst loading of complex 2 (0.01 mol%), afforded a series of 3‐arylcoumarins with a maximum of 92% yield and reusability up to five cycles. The present methodology is simple and easy to carry out at room temperature utilizing a green solvent (ethanol) in an open flask with a spectrum of aryl boronic acids. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, a method for the enantioselective reduction of unprotected 2‐alkylpyridines is reported for the first time. By using pinacolborane and an amide as reducing agents, a large number of 2‐alkylpiperidines were synthesized with high yields and excellent enantioselectivities via a cascade process involving 1,4‐hydroboration and subsequent transfer hydrogenation. The resulting products can be easily converted to natural alkaloids. [ABSTRACT FROM AUTHOR]