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The ruthenium‐catalyzed azide‐alkyne cycloaddition (RuAAC) gives access to 1,5‐disubstitued triazoles in a single atom‐economical step and offers advantages compared to its copper‐catalyzed counterpart in that both terminal and internal alkynes can be employed. This review summarizes recent findings in this field during the last eight years, covering mechanistic investigations, synthetic developments, as well as applications in medicinal chemistry, polymer synthesis and physical organic chemistry. [ABSTRACT FROM AUTHOR]

Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, epoxide opening, rearrangements, metathesis and cyclopropanation. Applications in the field of asymmetric synthesis are also discussed. [ABSTRACT FROM AUTHOR]

The transition to a circular economy requires that we adapt currently used chemical processes to the structurally diverse and often highly oxygenated precursors that are accessible from biomass. In this review, we highlight different examples of carbon–carbon bond formation using aromatics derived from bio-based sources, reported during 2015–2024. Examples of sustainable biomass building blocks include heterocycles such as furfural and hydroxymethylfurfural, obtained from carbohydrates, as well as lignin-based aromatics such as vanillin and eugenol. These have subsequently been applied in a variety of different types of carbon–carbon bond formation, including more classical methods such as aldol condensation and Morita–Baylis–Hillman reactions, but also employing transition metal catalysis, electrochemistry or photochemistry to create new C–C bonds. [ABSTRACT FROM AUTHOR]

Reports on a facile yet versatile, high-yield synthesis of S-alkyl and S-aryl ynethiol ethers from corresponding thiols. Finding an expanded application in synthesis.

Investigates reactions between meso dialdehydes and chiral Horner-Wadsworth-Emmons reagents. Asymmetric induction on three stereocenters; Use of derived products as building blocks of natural products; Selectivities; Absolute configurations of condensation products.

Describes a formal total synthesis of the fungal metabolite brefeldin A using asymmetric Pauson-Khand cyclization. Reactants for the reaction; Details on the step-by-step process of the reaction.

Review: 62 refs. [ABSTRACT FROM AUTHOR]

Biofouling is a general problem in marine applications. Copper has been used as an anti-biofouling agent in marine coatings for decades; however, its widespread use has resulted in regulatory restrictions due to high copper concentrations in harbors and areas with limited water circulation. Here we present a new approach for anti-fouling coatings using microparticles of poly(tris[(benzyltriazol)methyl]amine) (poly(TBTA)) polymers to absorb and control the interaction between a surface coating and the copper naturally present in seawater with the intention of creating a flux of copper across the water/coating interface. The preparation and characterization of microparticles of poly(TBTA) as well as hybrid PMMA: poly(TBTA) has been described to study the feasibility of tuning the copper-coordination properties of a generic marine coating using these paint-compatible microparticles. The properties of microparticles of poly(TBTA), PMMA and the PMMA: poly(TBTA) hybrid were therefore studied using cyclic voltammetry and NMR spectroscopy. It is demonstrated that the copper ions interact specifically with microparticles containing the coordinating polymer poly(TBTA) and that these microparticles have a high absorption capacity of more than 5 wt% for copper. [ABSTRACT FROM AUTHOR]

A short concise route to β-aminophosphine boranes is presented via the desymmetrization of prochiral phosphine boranes, forming P-chirogenic aldehydes that are rapidly transformed to the target compounds employing reductive amination under microwave irradiation. This sequence provides a modular route to P-chirogenic P,N ligands, and in addition, the intermediate aldehydes are versatile P-chiral building blocks for ligand design in general. An alternative pathway via the corresponding a-carboxyphosphines is also described. The ligands were subsequently evalutated in the asymmetric conjugate addition of diethylzinc to trans-β-nitrostyrene. [ABSTRACT FROM AUTHOR]

Abstract: An intermolecular Pauson–Khand reaction involving a carbohydrate scaffold having a pendant alkyne provides galactose derivatives with a cyclopentenone moiety in the C3-position in up to 85% yield. [Copyright &y& Elsevier]

Abstract: The reactivity of three polymer-bound cyclohexadienoic acid active esters was modified by complexation with iron tricarbonyl in order to evaluate their potential use as linker systems for solid phase chemistry. The best results were obtained with the tetrafluorophenol ester, which was slowly cleaved when 1equiv of amine was used, but could be rapidly cleaved with up to 94% yield when the amount of nucleophile was increased. [Copyright &y& Elsevier]

A palladium-catalyzed domino arylation-cyclization of biocatalytically derived cyclic 1,3-dienes is demonstrated. The reaction introduces a high degree of structural complexity in a single step, giving access to tricyclic tetrahydrofluorenones with full regio- and stereoselectivity. The transformation proceeds through a novel acylation-terminated Heck-type sequence, and quantum chemical calculations indicate that C–H activation is involved in the terminating acylation step. [ABSTRACT FROM AUTHOR]

Ir complexes of chiral phosphine-diamine ligands catalyse the hydrogenation and transfer hydrogenation of aryl-piperidin-4-yl methanones, and ketones bearing both an aryl group and secondary alkyl substituent with up to 98% e.e., and with substrate to catalyst ratios of up to 4000. [ABSTRACT FROM AUTHOR]

Abstract: Two different methods for the rapid microwave-assisted amination of halide-functionalized polymers were investigated. Nucleophilic substitution by phthalimide, followed by ring opening with methylamine to liberate the free amine, afforded amino-substituted polymers with up to 76% conversion. The second method involves nucleophilic substitution with azide ions and subsequent treatment with triphenylphosphine. The latter method was found to be more efficient, with up to 99% conversion in favourable cases and with a reaction time of 2×30min. [Copyright &y& Elsevier]

The structure of cis-[Mo(CO)4(PPh3)2] 1 was determined by F. A. Cotton, D. J. Darensbourg, S. Klein and B. W. S. Kolthammer, Inorg. Chem., 1982, 21, 1651–1655, with the space group P1̅. A second polymorph 2 is reported here, with the space group P21/c. The compounds differ in the interactions between the conformational chiral triphenylphosphine groups. In 1, there is π–π stacking between adjacent phenyl groups, whereas in 2, there are σ–π interactions instead. A search of the Cambridge Structural Database reveals that this is a relatively frequent occurrence in cis-bis-triphenylphosphine complexes and the phenomenon can be analysed by means of the C(ipso)–P–M–P torsion angles. The majority of compounds fall in the π–π stacking data area with torsion angles of 10–15° and 55–60°; however, for octahedrally coordinated metals, the optimum is a σ–π interaction at 40°/40°. This corresponds well to the values in 2: 46°/40°, but for 1, we instead find the torsion angles to be 11°/18°. There is indeed a small occurrence of these values as well in the data, and it appears that for 1, this conformation is stabilised by weak CO…H–C hydrogen bonds. Density functional theory (DFT) calculations indicate that 1 is the more stable polymorph by 72 kJ mol−1 but that the strain of the complexes (the difference between a relaxed molecule in the respective conformation and the structure in the crystal) is larger for 1 than for 2, further indicating that a special intermolecular interaction is responsible for the stability of this polymorph. In both polymorphs, the triphenylphosphines have the same conformational chirality, consistent with single-molecule calculations that predict racemic conformations to be substantially higher in energy for both σ–π interactions (+17 kJ mol−1) and π–π stacking (+30 kJ mol−1). [ABSTRACT FROM AUTHOR]

The ruthenium-catalyzed azide alkyne cycloaddition (RuAAC) affords 1,5-disubstituted 1,2,3-triazoles in one step and complements the more established copper-catalyzed reaction providing the 1,4-isomer. The RuAAC reaction has quickly found its way into the organic chemistry toolbox and found applications in many different areas, such as medicinal chemistry, polymer synthesis, organocatalysis, supramolecular chemistry, and the construction of electronic devices. This Review discusses the mechanism, scope, and applications of the RuAAC reaction, covering the literature from the last 10 years. [ABSTRACT FROM AUTHOR]

We have prepared novel [ η 4 ] and [ η 5 ] + tricarbonyliron complexes from an unusual enantiopure cyclohexadiene ligand that possesses a quaternary stereocentre; this in turn is prepared through biotransformation of an aromatic ring. The cyclohexadiene ligand initially possessed two hydroxyl groups, both of which could be substituted with other functionality by means of an overall [ η 4 ] → [ η 5 ] + → [ η 4 ] → [ η 5 ] + → [ η 4 ] sequence. From six novel tricarbonyliron complexes which have been prepared, three have been characterised by x-ray crystallography. The reaction sequence we describe is potentially of relevance to the synthesis of analogues of the anti-influenza drug oseltamivir. In addition, the failure of an attempted addition of a bulky nitrogen nucleophile to an [ η 5 ] + complex sheds light on the limits of reactivity for such additions. Thus, two bulky nucleophiles which are each known to add successfully to unencumbered [ η 5 ] + complexes seemingly cannot be added sequentially to adjacent positions on the cyclohexadiene ligand. [ABSTRACT FROM AUTHOR]

The article offers chemical equations related to an article on hydrogenation of cycloalkyl and heterocyclic ketones catalyzed by an iridium complex of a tridentate phosphine-diamine ligand by J.A. Fuentes and colleagues in a 2013 issue of the journal "Chemical Communications Volume 135."

A one-pot method for the functionalization of polyvinylbenzyl chloride with a tris-(benzyltriazolylmethyl)amine (TBTA) ligand via the copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) is reported, where the ligand is constructed simultaneously with its attachment to the polymer backbone. A hydrophobic TBTA polymer as well as co-polymers containing TBTA ligands were also prepared to demonstrate the possibility of tailoring the properties of the polymers. The polymers were characterized with FT-IR and NMR spectroscopy, elemental analysis, contact angle measurement, differential scanning calorimetry and thermal gravimetric analysis. The metal coordinating properties of films prepared from the polymers was also demonstrated using X-ray photoelectron spectroscopy and their structures inspected by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Coronaviruses raise serious concerns as emerging zoonotic viruses without specific antiviral drugs available. Here we screened a collection of 16671 diverse compounds for anti-human coronavirus 229E activity and identified an inhibitor, designated K22, that specifically targets membrane-bound coronaviral RNA synthesis. K22 exerts most potent antiviral activity after virus entry during an early step of the viral life cycle. Specifically, the formation of double membrane vesicles (DMVs), a hallmark of coronavirus replication, was greatly impaired upon K22 treatment accompanied by near-complete inhibition of viral RNA synthesis. K22-resistant viruses contained substitutions in non-structural protein 6 (nsp6), a membrane-spanning integral component of the viral replication complex implicated in DMV formation, corroborating that K22 targets membrane bound viral RNA synthesis. Besides K22 resistance, the nsp6 mutants induced a reduced number of DMVs, displayed decreased specific infectivity, while RNA synthesis was not affected. Importantly, K22 inhibits a broad range of coronaviruses, including Middle East respiratory syndrome coronavirus (MERS–CoV), and efficient inhibition was achieved in primary human epithelia cultures representing the entry port of human coronavirus infection. Collectively, this study proposes an evolutionary conserved step in the life cycle of positive-stranded RNA viruses, the recruitment of cellular membranes for viral replication, as vulnerable and, most importantly, druggable target for antiviral intervention. We expect this mode of action to serve as a paradigm for the development of potent antiviral drugs to combat many animal and human virus infections. [ABSTRACT FROM AUTHOR]

Non-natural peptides with structures and functions similar to natural peptides have emerged lately in biomedical as well as nanotechnological contexts. They are interesting for pharmaceutical applications since they can adopt structures with new targeting potentials and because they are generally not prone to degradation by proteases. We report here a new set of peptidomimetics derived from δ-peptides, consisting of n units of a 1,5-disubstituted 1,2,3-triazole amino acid (5Tzl). The monomer was prepared using ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) chemistry using [RuCl2Cp*] x as the catalyst, allowing for simpler purification and resulting in excellent yields. This achiral monomer was used to prepare peptide oligomers that are water soluble independent of peptide chain length. Conformational analysis and structural investigations of the oligomers were performed by 2D NOESY NMR experiments, and by quantum chemical calculations using the ωB97X-D functional. These data indicate that several conformations may co-exist with slight energetic differences. Together with their increased hydrophilicity, this feature of homo-5Tzl may prove essential for mimicking natural peptides composed of α-amino acids, where the various secondary structures are achieved by side chain effects and not by the rigidity of the peptide backbone. The improved synthetic method allows for facile variation of the 5Tzl amino acid side chains, further increasing the versatility of these compounds. [ABSTRACT FROM AUTHOR]

The slow dissociation of DNA threading intercalators makes them interesting as model compounds in the search for new DNA targeting drugs, as there appears to be a correlation between slow dissociation and biological activity. Thus, it would be of great value to understand the mechanisms controlling threading intercalation, and for this purpose we have investigated how the length of the bridging ligand of binuclear ruthenium threading intercalators affects their DNA binding properties. We have synthesised a new binuclear ruthenium threading intercalator with slower dissociation kinetics from ct-DNA than has ever been observed for any ruthenium complex with any type of DNA, a property that we attribute to the increased distance between the ruthenium centres of the new complex. By comparison with previously studied ruthenium complexes, we further conclude that elongation of the bridging ligand reduces the sensitivity of the threading interaction to DNA flexibility, resulting in a decreased AT selectivity for the new complex. We also find that the length of the bridging ligand affects the enantioselectivity with increasing preference for the ΔΔ enantiomer as the bridging ligand becomes longer. [ABSTRACT FROM AUTHOR]

A modular synthesis of P-chirogenrc α-alkoxyphosphine Iigands has been developed, allowing for the-variation of two of the three groups on phosphorus. Oxidation and concomitant desymmetrization of a prochiral alkyl- or aryldimethylphosphine borane afforded α-hydrosyphasphines, which were subsequently depcotonated and alkylated in a parallel fashion. The choice of base and temperature for the alkylaliun step was found to be crucial for the outcome of the reaction. Selected ligands were subsequently screened in palladium catalyzed ally tic substitution, affording product in good to excellent yield but moderate enantioselectivity, indicating that further optimization of the ligand structures is desirable to increase the stereoselectivity. [ABSTRACT FROM AUTHOR]

An experimentally simple sequential one-pot RuAAC reaction, affording 1,5-disubstituted 1H-1,2,3-triazoles in good to excellent yields starting from an alkyl halide, sodium azide, and an alkyne, is reported. The organic azide is formed in situ by treating the primary alkyl halide with sodium azide in DMA under microwave heating. Subsequent addition of [RuClCp*(PPh3)2] and the alkyne yielded the desired cycloaddition product after further microwave irradiation. [ABSTRACT FROM AUTHOR]

Abstract: To search for novel drugs against human respiratory syncytial virus (RSV), we have screened a diversity collection of 16,671 compounds for anti-RSV activity in cultures of HEp-2 cells. Two of the hit compounds, i.e., the N-(2-hydroxyethyl)-4-methoxy-N-methyl-3-(6-methyl[1,2,4]triazolo[3,4-a]phthalazin-3-yl)benzenesulfonamide (designated as P13) and the 1,4-bis(3-methyl-4-pyridinyl)-1,4-diazepane (designated as C15), reduced the virus infectivity with IC50 values of 0.11 and 0.13μM respectively. The concentration of P13 and C15 that reduced the viability of HEp-2 cells by 50% was 310 and 75μM respectively. Both P13 and C15 exhibited no direct virucidal activity or inhibitory effects on the virus attachment to cells. However, to inhibit formation of RSV-induced syncytial plaques P13 and C15 had to be present during the virus entry into the cells and the cell-to-cell transmission of the virus. The RSV multiplication in HEp-2 cells in the presence of P13 or C15 resulted in rapid selection of viral variants that were ∼1000 times less sensitive to these drugs than original virus. Sequencing of resistant viruses revealed presence of amino acid substitutions in the F protein of RSV, i.e., the D489G for C15-selected, and the T400I and N197T (some clones) for the P13-selected virus variants. In conclusion, we have identified two novel fusion inhibitors of RSV, and the detailed understanding of their mode of antiviral activity including selection for the drug resistant viral variants may help to develop selective and efficient anti-RSV drugs. [ABSTRACT FROM AUTHOR]

Abstract: Cationic iron carbonyl cyclohexadiene complexes were employed in the derivatization of the 3-OH position of unprotected and protected methyl β-d-galactopyranosides using two different approaches, giving access to galactopyranosides with an aromatic or cyclohexadienoic functionality in this position. [Copyright &y& Elsevier]

An asymmetric version of the Nicholas reaction involving the use of chiral phosphoramidite ligands has been developed. Treatment of a cobalt carbonyl complexed propargylic alcohol with two equivalents of the chiral ligand, followed by reaction with a silyl enol ether in the presence of a Lewis acid, afforded, after decomplexation, the desired product in up to 74% ee for the carbon-carbon bond forming step. [ABSTRACT FROM AUTHOR]

Abstract: Methyl β-d-galactoside was converted to the corresponding 3,4-O-stannylene acetal, which was selectively benzylated with 3-iodobenzyl bromide and coupled to a polymer-bound propargylic ether via a Sonogashira reaction. The polymer-bound carbohydrate substrate was cleaved from the resin with different carbon nucleophiles in a cobalt-mediated Nicholas reaction. The product 3-O-alkynylbenzyl galactosides were screened towards galectin-1, -3, -7, -8N and -9N in a competitive fluorescence polarisation assay. Particularly potent inhibitors were identified against galectin-7 with affinity enhancements up to one order of magnitude due to the 3-O-alkynylbenzyl moiety. [Copyright &y& Elsevier]

The first example of a Nicholas reaction on solid phase is reported, involving the reaction of cobalt complexes of polymer-bound alkynols with different nucleophiles in the presence of a Lewis acid, to form carbon-oxygen or carboncarbon bonds. [ABSTRACT FROM AUTHOR]