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A novel protocol was developed for the construction of highly functionalized pyridin-2(1H)-ones from 3-formylchromones, ethyl 2-(pyridin-2-yl)acetate derivatives and amines via a complex multicomponent cascade reaction involving targeted duplicated ring-opening and duplicated cyclization reactions which form skeleton-reorganized target compounds. A series of pyridin-2(1H)-ones were produced by this reaction accompanied by the formation of three bonds (one C-N and two C-C bonds) and the cleavage of one bond in one step. This protocol can be used in combinatorial and parallel syntheses of various pyridin-2(1H)-ones with potent biological activity. The advantages of this approach include simple and practical operation (multicomponent one-pot), high yields (up to 91%), and products with potential biological activity. [ABSTRACT FROM AUTHOR]

In our study, a method for the epoxidation of cis‐cyclooctene was researched using a series of Lindqvist type POMs Cp*2MoxW6−xO17 (x=0, 2, 4, 6) and [Cp*MoxW6−xO18]− (x=0, 1, 5, 6) as a catalyst in the presence of 30 % H2O2 as a green oxidant. This catalytic system containing polyoxometalates and H2O2 has applied the most succesful system in obtaining epoxide product with excellent yields for cis‐cyclooctene in acetonitrile at 55 °C. Maximum epoxidation efficiency of 99 % was observed under optimized conditions for Ph4P[Cp*MoW5O18] (2c). [ABSTRACT FROM AUTHOR]

It is necessary to design and develop simpler, more efficient, and cleaner synthetic methodologies to prepare increasingly complex molecules. One interesting strategy is multicatalysis. The aim of this study was to synthesize a multicatalytic hybrid system by the immobilization of H3PW12O40 (HPW), a polyoxometalate, on ionic liquid-functionalized mesoporous silica (SBA-15 or MCF). The resulting catalysts were characterized by different techniques, including N2 adsorption–desorption, Boehm titration of the acid site, SEM-EDS, FT-IR, XPS, CP-MAS, and NMR. To test the active site acid-oxidant duality of HPW, 2-pyridones were synthesized in a one-pot methodology with auto-tandem catalysis involving the ring-opening/ring-closure/oxidation sequence of 4H-pyrans. The morphology of the support structure affects the duality of HPW. Whereas the MCF complex favors oxidation, the SBA-15 complex favors Brønsted acidity (finding greater oxidation when adding water). The hybrid catalyst was recovered and reused for eight consecutive reaction cycles with no significant loss in activity. [ABSTRACT FROM AUTHOR]

Front Cover: C-H Activation Based Functionalization of Furfural Derivatives (Eur. J. Org. Keywords: Biomass; Catalysis; C-H Activation; Furfural; Transition metal EN Biomass Catalysis C-H Activation Furfural Transition metal 1 1 1 11/22/22 20221118 NES 221118 B The Front Cover b sketches the generation of the platform molecules furfural and 5-hydroxymethylfurfural from agricultural waste, and their subsequent valorization by transformation into value-added chemicals, as imagined by artist Monica Rizzi. Biomass, Catalysis, C-H Activation, Furfural, Transition metal. [Extracted from the article]

Furfural and related compounds are building blocks of industrial interest, obtained from raw biomass. Their use as precursors of basic and fine chemicals has gained increasing attention as a green alternative to petroleum‐derived compounds. Several works have reported the functionalization of furfurals to obtain a wider range of chemicals, opening up new synthetic possibilities and applications, ranging from biofuels to pharmaceuticals. Among these works, processes based on C−H activation are the most attractive ones for their atom economy and the possibility to use non‐activated substrates. This minireview summarizes the reported methods of direct C−H functionalization of furfurals without prior modification of the redox state of the aldehyde function. In particular, the transition metal catalyzed functionalization of each bond of the heteroaromatic nucleus of these molecules is systematically discussed, as well as examples of C−H transformations of the aldehyde function. [ABSTRACT FROM AUTHOR]

Phosphanylferrocene chalcogenides remain long overshadowed by their more common and very successful phosphane counterparts. However, they also exhibit unique coordination behavior, which differs from that of the parent phosphanes due to changed donor and steric properties, and exert favorable catalytic properties. This review attempts to showcase the chemistry of phosphanylferrocene chalcogenides with particular emphasis on their applications in coordination chemistry and catalysis. Attention is also paid to the corresponding mixed‐donor phosphane‐phosphane chalcogenide ligands, which can serve as genuine examples of versatile hybrid donors with rich coordination chemistry and attractive use in catalysis. [ABSTRACT FROM AUTHOR]

Isobutanal is a high value bulk material that, in principle, could be produced with 100 % atom‐economy by isoselective hydroformylation of propylene with syngas. However, leading industrial Rh‐ and Co‐catalyzed hydroformylation methods preferentially form n‐butanal over the iso‐product, and methods offering isoselectivity remain underdeveloped. Here we report an iodide‐assisted Pd‐catalyzed hydroformylation of propylene that produces isobutanal with unprecedented levels of selectivity. The method involves PdI2, simple alkyl monophosphines, such as tricyclohexylphosphine, and common green solvents, enabling the title reaction to occur with isoselectivity in up to 50 : 1 iso/n product ratios under industrially relevant conditions (80–120 °C). The catalytic and preliminary mechanistic experiments indicate a key role of the iodide anions in both the catalytic activity and the isoselectivity. [ABSTRACT FROM AUTHOR]

Transition metal mediated C–H functionalization has been highly relevant in organic synthesis for decades. However, sustainability as an inherent feature in such transformations remains under-developed. Through a varied approach, we have explored metal-centered catalysis practiced via mechanochemistry and under microwave-irradiation, both strictly without the use of any toxic organic solvents. In some sections of this report, we shed light upon C–H functionalizations carried out in the universal and clean solvent water, as well as in neat, solvent-devoid conditions. Different metal centers like Pd, Rh, Ru, Cu, Fe, Co and a spectrum of mechanistic pathways that have accomplished these reactions in an unconventional but green protocol, are discussed extensively. This serves as an attempt to address the challenges in environmental preservation while carrying out organic reactions, and to encourage innovative versatile ideas. Our review collectively presents the endeavours that have introduced hazard-free methodologies in these C–H activation pathways. [ABSTRACT FROM AUTHOR]

Metal‐catalyzed C−H activations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre‐functionalized substrates and minimize waste generation. Great challenges reside in the control of selectivities, the utilization of unbiased hydrocarbons, and the operation of atom‐economical dehydrocoupling mechanisms. An especially mild borylation of benzylic CH bonds was developed with the ligand‐free pre‐catalyst Co[N(SiMe3)2]2 and the bench‐stable and inexpensive borylation reagent B2pin2 that produces H2 as the only by‐product. A full set of kinetic, spectroscopic, and preparative mechanistic studies are indicative of a tandem catalysis mechanism of CH‐borylation and dehydrocoupling via molecular CoI catalysts. [ABSTRACT FROM AUTHOR]

Oxide perovskites have emerged as an important class of materials with important applications in many technological areas, particularly thermocatalysis, electrocatalysis, photocatalysis, and energy storage. However, their implementation faces numerous challenges that are familiar to the chemist and materials scientist. The present work surveys the state-of-the-art by integrating these two viewpoints, focusing on the critical role that defect engineering plays in the design, fabrication, modification, and application of these materials. An extensive review of experimental and simulation studies of the synthesis and performance of oxide perovskites and devices containing these materials is coupled with exposition of the fundamental and applied aspects of defect equilibria. The aim of this approach is to elucidate how these issues can be integrated in order to shed light on the interpretation of the data and what trajectories are suggested by them. This critical examination has revealed a number of areas in which the review can provide a greater understanding. These include considerations of (1) the nature and formation of solid solutions, (2) site filling and stoichiometry, (3) the rationale for the design of defective oxide perovskites, and (4) the complex mechanisms of charge compensation and charge transfer. The review concludes with some proposed strategies to address the challenges in the future development of oxide perovskites and their applications. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of novel triphosphine calix[6]arene ligands. These supramolecular wheels, with recognition features governed by the hydrogen‐bonding domain, were employed to synthesize multitasking trinuclear gold(I) complexes as a new platform for the synthesis of interwoven (pseudo)rotaxane species. In parallel, the multivalent, metal‐bonded upper rim displayed catalytic features promoting highly selective gold‐catalyzed cycloisomerization reactions of 1,6‐enynes. [ABSTRACT FROM AUTHOR]

The stereoselective synthesis of P‐chirogenic diphosphinotriazoles using ephedrine methodology was described. The coordination behavior of these compounds as P,P‐ligands has been demonstrated by the preparation as well as the spectroscopic and X‐ray crystallographic analyses of a palladium complex. The efficiency of these new P‐chirogenic diphosphines in the palladium‐catalyzed asymmetric allylic substitution reaction was also evaluated. [ABSTRACT FROM AUTHOR]

Kinetic resolution using biocatalysis has proven to be an excellent complementary technique to traditional asymmetric catalysis for the production of enantioenriched compounds. Resolution using oxidative enzymes produces valuable oxygenated structures for use in synthetic route development. This Minireview focuses on enzymes which catalyse the insertion of an oxygen atom into the substrate and, in so doing, can achieve oxidative kinetic resolution. The Baeyer–Villiger rearrangement, epoxidation, and hydroxylation are included, and biological advancements in enzyme development, and applications of these key enantioenriched intermediates in natural product synthesis are discussed. [ABSTRACT FROM AUTHOR]

Dioxo‐molybdenum complexes have been reported as catalysts for the deoxydehydration (DODH) of diols and polyols. Here, we report on the DODH of diols using [Cp*MoO2]2O as catalyst (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl). The DODH reaction was optimized using 2 mol % of [Cp*MoO2]2O, 1.1 equiv. of PPh3 as reductant, and anisole as solvent. Aliphatic vicinal diols are converted to the corresponding olefins by [Cp*MoO2]2O in up to 65 % yield (representing over 30 turnovers per catalyst) and 91 % olefin selectivity, which rivals the performance of other Mo‐based DODH catalysts. Remarkably, cis‐1,2‐cyclohexanediol, which is known as quite a challenging substrate for DODH catalysis, is converted to 30 % of 1‐cyclohexene under optimized reaction conditions. Overall, the mass balances (up to 79 %) and TONs per Mo achievable with [Cp*MoO2]2O are amongst the highest reported for molecular Mo‐based DODH catalysts. A number of experiments aimed at providing insight in the reaction mechanism of [Cp*MoO2]2O have led to the proposal of a catalytic pathway in which the [Cp*MoO2]2O catalyst reacts with the diol substrate to form a putative nonsymmetric dimeric diolate species, which is reduced in the next step at only one of its Mo‐centers before extrusion of the olefin product. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis of a new P‐chirogenic triazole‐based phosphine according to the ephedrine methodology. Upon reaction with late transition‐metal derivatives, RhI and PdII, phosphine‐triazole forms complexes with bidentate P,N coordination, as demonstrated by spectroscopic and X‐ray crystallographic analyses. First experiments in asymmetric catalysis showed the catalytic potential of this new chiral P,N‐type ligand. [ABSTRACT FROM AUTHOR]

Annulative η3‐allylpalladium chemistry has been a longstanding trending research topic since the 80's. Nowadays, this research area is still providing challenges to the catalysis community leading to the development original and brand‐new transformations. Several reaction partners have been used as precursors for η3‐allylpalladium species, namely allyl diacetates, allyl monoacetates, 3‐acetoxy‐2‐trimethylsilylmethyl‐1‐propene (ASMP), alkylidene cyclopropanes (ACPs), vinyl cyclopropanes (VCPs), vinyl aziridines, and vinyl epoxides. This minireview is intended to show the recent developments in the field of annulative η3‐allylpalladium chemistry with emphasis on new reactivity, enantioselective transformations as well as potential applications in total synthesis. [ABSTRACT FROM AUTHOR]

Artificial enzymes have broad applications in catalysis and can be used to help understand catalytic mechanisms. Nanoceria has various enzyme‐mimetic properties that depend on the relative content of Ce3+ and Ce4+. In this context, CeO2 nanotubes was investigated as catalase mimics for water oxidation. The photosensitizer 5,10,15,20‐meso‐tetra(4‐carboxyphenyl) porphyrin (TCPP) was facilely embedded in CeO2 nanotubes (TCPP@CeO2 NTs), and photoinduced charge transfer was shown to occur between the strongly coupled TCPP and CeO2, which leads to effective charge separation and charge redistribution within the hybrids. As a consequence, formation of H2O2, a competing process in water oxidation and a key factor that affects the oxidative stability of photoelectrodes, was effectively inhibited on TCPP@CeO2 NTs. These findings show that enzyme mimics can be used for the selective generation of reactive oxygen species, and therefore to control the kinetics of water oxidation. [ABSTRACT FROM AUTHOR]

Atom Transfer Radical Polymerization (ATRP), a metal‐catalyzed process, is a most powerful method for macromolecular engineering, producing polymers with targeted and low‐dispersity molar masses and with high chain‐end fidelity. This is due to the persistent radical effect, which dramatically reduces the spontaneous radical terminations, prolonging the lifetime of radical chains and the concurrent growth of all polymer chains. Two additional reaction modes that involve metals and organic radicals, however, may negatively affect the controlled polymerization. These are the Catalyzed Radical Termination (CRT) and the Reductive Radical Termination (RRT) and were shown to be particularly important for the polymerization of acrylate monomers. The scope and the mechanistic investigations carried out to elucidate how these processes interplay with ATRP and with each other are outlined in this Minireview. [ABSTRACT FROM AUTHOR]

C−H activation and functionalization have caused a paradigm shift in molecular design as a result of its selective and atom‐economical nature. Despite significant major advances, C−H functionalization regime had the disadvantage of employing (super) stoichiometric amounts of expensive and toxic metal oxidants for oxidative functionalization. Hence, various protocols were introduced to improve the sustainability of C−H bond functionalization, such as employing molecular oxygen, metal oxidants or tethered oxidants that get cleaved during the reaction, in addition to the use of suitable solvents or additives. The most recent and proficient advance is the use of electro‐ or photo‐redox catalysis. In this Review, we highlight the recent advances towards a green catalytic approach for oxidative C−H bond functionalization using light and photosensitizers or electricity as sources of oxidant to regenerate the active species. [ABSTRACT FROM AUTHOR]

Fluorinated bis‐ and tris(pyrazolyl)boratocopper complexes catalyze the nitrene insertion to C−H bonds of aromatic hydrocarbons efficiently producing amination products in good to excellent yields at room temperature. Imidoiodanes, PhI=NTs (Ts=p‐toluenesulfonyl) and PhI=NNs (Ns=p‐nitrophenylsulfonyl) serve as the nitrene source. The bis(pyrazolyl)borate catalyst [H2B(3,5‐(CF3)2Pz)2]Cu(NCMe) with PhI=NNs produced the arene C−H functionalized product of mesitylene in 87 % yield with only trace amounts of benzylic C−H insertion. The use of [H2B(3,5‐(CF3)2‐4‐(NO2)Pz)2]Cu(NCMe) that has an even weakly donating pyrazolate generated the arene C−H insertion product exclusively. The tris(pyrazolyl)borate complex [HB(3,5‐(CF3)2Pz)3]Cu(NCMe), in contrast, generated the benzylic amination product from mesitylene and PhI=NNs in 82 % yield with only very minor amounts of arene C−H functionalization. DFT calculations suggest that Cu‐nitrene moiety generated from [HB(3,5‐(CF3)2Pz)3]Cu(NCMe) and PhI=NNs activates the benzylic C−H bond of mesitylene via a hydrogen atom abstraction (HAA) followed by a radical rebound (RR) pathway, whereas the functionalization of sp2 C−H bonds of mesitylene by [H2B(3,5‐(CF3)2Pz)2]Cu(NNs) ensues possibly via a nitrene addition to the arene core. [ABSTRACT FROM AUTHOR]

A mild, environment-friendly protocol has been developed to carry out the [4+2] annulation of aryl amides with unactivated olefins. A range of sterically and electronically diverse aryl amides and unactivated olefins were successfully employed under the developed conditions to get a variety of dihydroisoquinolinones in good-to-excellent yields. [ABSTRACT FROM AUTHOR]

On the 1H NMR timescale, 2,2′‐biindolyls with (R)‐configured (1‐alkoxyprop)‐2‐yl, (1‐hydroxyprop)‐2‐yl, or (1‐siloxyprop)‐2‐yl substituents at C‐1 and C‐1′ are atropisomerically stable at <0 °C and interconvert at >30 °C. A 2,2′‐biindolyl (R,R)‐17 a of that kind and achiral (!) brominating reagents gave the atropisomerically stable 3,3′‐dibromobiindolyls (M)‐ and/or (P)‐18 a at best atropselectively—because of point‐to‐axial asymmetric inductions—and atropdivergently, exhibiting up to 95 % (M)‐ and as much (P)‐atropselectivity. This route to atropisomerically pure biaryls is novel and should extend to other substrates and/or different functionalizations. The dibromobiindolyls (M)‐ and (P)‐18 a furnished the biindolyldiphosphanes (M)‐ and (P)‐14 without atropisomerization. These syntheses did not require the resolution of a racemic mixture, which distinguishes them from virtually all biaryldiphosphane syntheses known to date. (M)‐ and (P)‐14 acted as ligands in catalytic asymmetric allylations and hydrogenations. Remarkably, the β‐ketoester rac‐25 c was hydrogenated trans‐selectively with 98 % ee; this included a dynamic kinetic resolution. Locking a labile atropisomer: The biindolyl (R,R)‐2 consists of diastereomeric atropisomers, which interconvert on the NMR timescale at +30 °C but not at −10 °C. (R,R)‐2 was dibrominated providing the biindolyls 1 (M)‐ or (P)‐selectively, depending on the achiral reagent. The two dibromides were elaborated into atropisomerically pure biindolyldiphosphanes, which induced higher ee values than BINAP in some Ru‐catalyzed β‐ketoester hydrogenations. [ABSTRACT FROM AUTHOR]

Abstract: A mild and selective C(sp3)−H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C−H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (−)‐ambroxide, pregnenolone acetate, (+)‐sclareolide, and artemisinin, exemplifies the utility of this new method. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbenes (NHCs) are widely used as ligands in catalysis by transition metal complexes. The catalytic activity of transition metal NHC complexes is much higher than that of the transition metal complexes bearing the phosphine and nitrogen-containing ligands. They show excellent catalytic performance in different transformations of the organic compounds, especially in the carbon-carbon and carbon-element bond forming reactions. Palladium NHC complexes are very efficient catalysts for the cross-coupling reactions. On the other hand, nickel is less expensive and regarded as a promising alternative to palladium and, therefore, it attracts increasing attention from the researches. The present review is focused on the recent advances in the synthesis of N-heterocyclic carbene complexes of nickel and palladium and their application in catalysis of cross-coupling reactions of organic, organoelement and organometallic compounds with organic halides. [ABSTRACT FROM AUTHOR]

A facile and general method for the stereoselective synthesis of (E)-2-aryl- (or vinyl)methylidene- 1,4-benzodiazepin-5-ones has been developed by means of palladium/charcoal-catalyzed reactions between aryl (or vinyl) halides/triflates and 2-aminotosyl (or nosyl/brosyl/mesyl)-N-alkyl-N- (prop-2-ynyl)benzamides. Replacing the benzamide unit in the latter substrate by its benzylamine analogue and subsequent reaction with aryl iodides under the same reaction conditions resulted in the formation of (E)-2-aryl- (or vinyl)methylidene-1,4- benzodiazepines. The reaction mechanism involves trans-aminopalladation as a key step during cyclization (7-exo-dig) ensuring exclusive (E)-stereochemistry of the products. The method is fast, operationally simple, totally regio- and stereoselective, and uses readily available substrates with varied structures and low cost Pd/C instead of costly palladium as catalyst. Furthermore, simple base-induced isomerization of the exocyclic double bond of the 1,4- benzodiazepin-5-one products yielded their endocyclic isomers. [ABSTRACT FROM AUTHOR]

Despite the growing interest in iron catalysis and hydroamination reactions, iron-catalyzed hydroamination of unprotected primary aliphatic amines and unactivated alkenes has not been reported to date. Herein, a novel well-defined four-coordinate β-diketiminatoiron(II) alkyl complex is shown to be an excellent precatalyst for the highly selective cyclohydroamination of primary aliphatic alkenylamines at mild temperatures (70-90 °C). Both empirical kinetic analyses and the reactivity of an isolated iron(II) amidoalkene dimer, [LFe(NHCH2CPh2CH2CHCH2)]2 favor a stepwise σ-insertive mechanism that entails migratory insertion of the pendant alkene into an iron-amido bond associated with a rate-determining aminolysis step. [ABSTRACT FROM AUTHOR]

A dual platinum- and pyrrolidine-catalyzed direct allylic alkylation of allylic alcohols with various active methylene compounds to produce products with high monoallylation selectivity was developed. The use of pyrrolidine and acetic acid was essential, not only for preventing undesirable side reactions, but also for obtaining high monoallylation selectivity. [ABSTRACT FROM AUTHOR]

Thirteen different symmetric and asymmetric phosphinesulfonato palladium complexes ([{( X 1-Cl)-μ-M} n], M=Na, Li, 1=X(P^O)PdMe) were prepared (see Figure 1). The solid-state structures of the corresponding pyridine or lutidine complexes were determined for (MeO)2 1-py, ( iPrO)2 1-lut, (MeO,Me2) 1-lut, (MeO)3 1-lut, CF3 1-lut, and Ph 1-lut. The reactivities of the catalysts X 1, obtained after chloride abstraction with AgBF4, toward methyl acrylate (MA) were quantified through determination of the rate constants for the first and the consecutive MA insertion and the analysis of β-H and other decomposition products through NMR spectroscopy. Differences in the homo- and copolymerization of ethylene and MA regarding catalyst activity and stability over time, polymer molecular weight, and polar co-monomer incorporation were investigated. DFT calculations were performed on the main insertion steps for both monomers to rationalize the effect of the ligand substitution patterns on the polymerization behaviors of the complexes. Full analysis of the data revealed that: 1) electron-deficient catalysts polymerize with higher activity, but fast deactivation is also observed; 2) the double ortho-substituted catalysts (MeO)2 1 and (MeO)3 1 allow very high degrees of MA incorporation at low MA concentrations in the copolymerization; and 3) steric shielding leads to a pronounced increase in polymer molecular weight in the copolymerization. The catalyst properties induced by a given P-aryl (alkyl) moiety were combined effectively in catalysts with two different non-chelating aryl moieties, such as c HexO/(MeO)2 1, which led to copolymers with significantly increased molecular weights compared to the prototypical MeO 1. [ABSTRACT FROM AUTHOR]

Arenetricarbonyl metal complexes ([–phM(CO)3–] and [–biphM(CO)3–]; ph = phenylene, biph = biphenylene, M = Mo, Cr) constructed within Zr-based MOFs act as highly active and selective catalysts for epoxidation of cyclooctene. Catalytic activities of these complexes are enhanced with increasing the pore sizes of Zr-based MOFs. [ABSTRACT FROM AUTHOR]

The catalytic activity of [Cp*2M2O5] (M = Mo, W; Cp* = pentamethylcyclopentadienyl) for the homogeneous epoxidation of a solution of cyclooctene in MeCN/toluene follows the order Mo >> W when using tert-butyl hydroperoxide (TBHP)/decane as oxidant, in contrast to the inverse order (W >> Mo) when using aqueous H2O2 as oxidant. The catalytic activity for the Mo system strongly depends on the solvent used to deliver the oxidant (TBHP/decane >> TBHP/H2O). The low activity of the W system is also decreased when using TBHP/water in place of TBHP/decane. For both metals, H2O2/H2O is a better oxidant than TBHP/H2O. However, whereas the Mo-based catalyst is much more active for the TBHP/decane epoxidation in spite of the lower TBHP oxidizing power (TBHP/decane > H2O2/H2O > TBHP/H2O), the W-based system is much more active for the H2O2/H2O epoxidation in spite of the negative effect of water (H2O2/H2O > TBHP/decane > TBHP/H2O). The kinetic profile of the TBHP/decane epoxidation process is affected by product inhibition. Initial rate measurements show that the rate law is first order with respect to substrate and has saturation behavior with respect to the oxidant. [ABSTRACT FROM AUTHOR]