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Silver has unique electrical, catalytic, and plasmonic characteristics and has been widely sought for fabrication of nanostructures. The properties of silver nanostructures are intimately coupled to the structure of silver crystals. Two crystal structures are known for silver: the stable (ground) state cubic face centered 3C-Ag structure and the metastable hexagonal 4H-Ag structure. Recently, Chackraborty et al. [J. Phys.: Condens. Matter 23, 325401 (2011)] discovered a low density, highly reactive metastable hexagonal 2H-Ag structure accessible during electrodeposition of silver nanowires in porous anodic alumina templates. This 2H-Ag structure has enhanced electrical and catalytic characteristics. In the present work we report template-free synthesis of silver nanoplates with the metastable 2H-Ag crystal structure, which appears together with the ground 3C-Ag and the metastable 4H-Ag structures in a two-phase solution synthesis with citric acid as the capping agent. The capacity of citric acid to stabilize both the stable and the metastable structures is explained by its preferential binding to the close packed facets of Ag crystals, which are the (111) planes for 3C-Ag and the (0001) planes for 4H-Ag and 2H-Ag. Nanoplate morphology and structure are characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The synthesized nanoplates have thickness from 15 to 17 nm and edge length from 1 to 10 µm. Transmission electron microscopy selected area electron diffraction is used to uniquely identify and distinguish between nanoplates with 2H-Ag or 4H-Ag or 3C-Ag structures. [ABSTRACT FROM AUTHOR]

The direct construction of C-O bond by C-H activation is a highly efficient and practical method for the synthesis of esters, ethers, and hydroxy compounds. As compared to the conventional method of mutual functional group conversion, the C-H activation method provides not only improved atomic economy and reduced number of synthetic steps but also greatly improved overall yield of multistep syntheses. Studies of C-H activation to construct C-O bonds are crucial in the field of organic synthesis and catalysis research, and they have already been one of the research hotspots in related fields. According to the current trends in the development of C-H activation, different reaction types and different reaction conditions are classified in this review, and the latest advances in C-H activation to form C-O bonds are discussed. [ABSTRACT FROM AUTHOR]

Compared to homogeneous catalysis, heterogeneous catalysis allows for ready separation of products from the catalyst and thus reuse of the catalyst. C-C coupling is typically performed on a molecular catalyst which is mixed with reactants in liquid phase during catalysis. This homogeneous mixing at a molecular level in the same phase makes separation of the molecular catalyst extremely challenging and costly. Here we demonstrated that a TiO2-based nanoparticle catalyst anchoring singly dispersed Pd atoms (Pd1/TiO2) is selective and highly active for more than 10 Sonogashira C-C coupling reactions (R≡CH + R′X → R≡R′; X = Br, I; R′ = aryl or vinyl). The coupling between iodobenzene and phenylacetylene on Pd1/TiO2 exhibits a turnover rate of 51.0 diphenylacetylene molecules per anchored Pd atom per minute at 60 °C, with a low apparent activation barrier of 28.9 kJ/mol and no cost of catalyst separation. DFT calculations suggest that the single Pd atom bonded to surface lattice oxygen atoms of TiO2 acts as a site to dissociatively chemisorb iodobenzene to generate an intermediate phenyl, which then couples with phenylacetylenyl bound to a surface oxygen atom. This coupling of phenyl adsorbed on Pd1 and phenylacetylenyl bound to Oad of TiO2 forms the product molecule, diphenylacetylene. [ABSTRACT FROM AUTHOR]

The aim of this study was to discover the unique volatile compositional traits of retail milk from different production systems. Forty-four retail milk samples were analyzed, including organic milk (n = 10), conventional milk (n = 14) and pasture milk (n = 20) from winter (n = 22) and summer (n = 22). Proton transfer reaction quadrupole mass spectrometry (PTR-(Quad)MS) was utilized to obtain the mass-resolved fingerprints (76 masses per sample) of volatile organic compounds (VOCs). Principal component analysis (PCA) and analysis of variance (ANOVA) were performed to evaluate the differences between the groups. The production systems were characterized by six masses, while season showed larger differences, with twenty-two masses discriminating between the milks. For 2 masses, a significant interaction of systems and seasons was observed. The chemical formula of these VOC masses were tentatively identified by Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-(ToF)MS). These results illustrate that the type of feed is reflected in the VOC composition of milks. [ABSTRACT FROM AUTHOR]

A convenient synthesis of 2-aminobenzothiazoles, starting from aryl isothiocyanates and formamides under metal-free conditions, is described. Various secondary and tertiary amine- and even α-amino acid-derived formamides can be used as amino sources in this process. Mechanistic studies suggest that the reaction is initiated by decarbonylative aminyl radical formation in the presence of n-Bu4NI and TBHP, followed by aminyl radical addition to isothiocyanates and cyclization via sulfur centred radical intermediates. [ABSTRACT FROM AUTHOR]

An efficient one pot synthesis for the construction of novel naphtho[2,1-b]furan-2,5-diones and benzo[de]chromene-2,6-diones using copper(i)–Y zeolite catalyzed reaction of N-sulfonylketenimine with 2-hydroxy-1,4-naphthoquinone and 5-hydroxy-1,4-naphthoquinone followed by the elimination of p-toluenesulfonamide is reported. The intermediate N-sulfonylketenimine, generated by (3+2) cycloaddition/ring-opening reaction/retro-Wolff rearrangement, cascade, and annulation, promotes the reaction involving the inter- and intramolecular nucleophilic addition/dehydration followed by hydrolysis and elimination of p-toluenesulfonamide to afford the target products in good yield. [ABSTRACT FROM AUTHOR]

A nanoscale “domain growth” mechanism was proposed based on experimental facts to describe the formation process of macro–meso–microporous HKUST-1 with 3-dimensional networks. [ABSTRACT FROM AUTHOR]

The reaction of L1H {L1H = 3-(N9-guaninyl)propionic acid} with Me3SnCl or (n-Bu3Sn)2O afforded the 1D coordination polymers, [Me3Sn(L1)]n (1) and [n-Bu3Sn(L1)]n (2) respectively. A reaction between L2H {L2H = 3-(N7-guaninyl)propionic acid} with Me3SnCl also afforded a 1D coordination polymer, [Me3Sn(L2)]n (3). A similar reaction between L3H [uracil-6-carboxylic acid] with (Ph3Sn)2O in a 2 : 1 ratio afforded a dimer [(n-Bu3SnL3)2·H2O] (4). A mononuclear compound [Me3Sn(L4)·H2O] (5) was obtained in a 1 : 1 reaction of 3-{N9-(2-aminopurinyl)}propanoic acid (L4H) with Me3SnCl. Complexes 1–5 show rich supramolecular structures in the solid state as a result of several intermolecular interactions. Thus, in the one-dimensional coordination polymer 3, triple hydrogen bonding (G≡G), between inter-chain guanine units has been observed. Similarly a homo orotatequartet has been observed in 4 as a result of intermolecular interactions. [ABSTRACT FROM AUTHOR]

This account describes the endeavors made by our group concerning the synthesis of aziridines and azetidin(on)es and their use as novel building blocks for the preparation of nitrogen-containing organofluorine compounds. The majority of contributions, covered in the first part, comprises the study of fluorinated small-ring substrates, focusing on both their synthesis and their synthetic applicability for further transformations. These investigations revealed a pronounced effect of fluorine on the overall reactivity of small-ring azaheterocycles, often resulting in a different behavior compared with that of their nonfluorinated counterparts. In the second part, contributions are covered dealing with the transformation of nonfluorinated small rings into fluorinated target molecules upon treatment with fluorinated reagents. 1 Introduction 2 Synthesis and Reactivity of Fluorine-Containing Aziridines and Azetidines 2.1 Aziridines 2.2 Azetidines 3 Synthesis of Fluorine-Containing Nitrogen Compounds Starting from Nonfluorinated Aziridines and Azetidines 3.1 Aziridines 3.2 Azetidines 4 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Peracetic acid promoted C-Se coupling reaction of arenes with diselenides under metal-free and solvent-free conditions has been described. The resulting selenide ethers were obtained in good to ex- cellent yields. Peracetic acid provided the selenide ethers via sp² C-H selenation whereas previously in case of DTBP sp³ C-H selenation was observed. [ABSTRACT FROM AUTHOR]

This account aims to give a description of the usefulness of diaryliodonium salts in organic chemistry, including their synthesis and applications in the presence and absence of transition-metal catalysts. Herein, we briefly summarize the structural properties and reactivity of diaryliodonium salts. We describe several applications of these hypervalent reagents including metal-free arylations of C-, O-, N- and S-nucleophiles. The synthesis and functionalization of aromatic and heteroaromatic systems via copper- and palladium-catalyzed transformations are also discussed in this account. 1 Introduction 2 Structural Properties and Reactivity 3 Applications of Diaryliodonium Salts in Organic Syntheses 3.1 Transition-Metal-Free Arylations of Heteroatom and Carbon Nu- cleophiles 3.1.1 Arylation of Oxygen Nucleophiles 3.1.1.1 Arylation of (Hetero)aromatic Alcohols 3.1.1.2 Arylation of Aliphatic Alcohols 3.1.1.3 Arylation of Acids 3.1.2 Arylation of Nitrogen Nucleophiles 3.1.2.1 N-Arylation of Amines and Amides 3.1.2.2 N-Arylation of Heterocycles 3.1.3 Arylation of Sulfur Nucleophiles 3.1.4 Arylation of Inorganic Anions 3.1.5 Arylation of Carbon Nucleophiles 3.1.5.1 Electron-Rich Heterocycles 3.1.5.2 Arylation of Carbonyl and Nitro Compounds 3.2 Synthesis and Functionalization of Aromatic and Heteroaromatic Molecules with Diaryliodonium Salts in the Presence of Copper and Palladium Catalysts 3.2.1 C-H Functionalizations by Copper-Catalyzed C-H Arylations 3.2.2 Copper-Catalyzed Cyclization of Unsaturated Compounds with Diaryliodonium Salts 3.2.3 Palladium-Catalyzed Arylations 3.2.3.1 Electrophilic Palladation and Arylation 3.2.3.2 Directing-Group-Assisted C-H Bond Activation and Arylation 4 Conclusion [ABSTRACT FROM AUTHOR]

ABSTRACT Herein we present the synthesis and polycondensation of mono- and di- N-protected, bis-substituted tri(benzamide)s with the aim to create large, tubular helices. We synthesized 2,4-dimethoxy and 2,5-bis-TEGylated aminobenzoic acid derivatives as bent and linear monomers and introduced p-methoxybenzyl (PMB) amide protecting groups to the oligobenzamide backbone. An iterative coupling strategy allowed for sequence control, giving rise to oligomers consisting of one bent and two linear monomers. The resulting meta- para- para-linked aromatic trimers carried either one or two PMB-protecting groups. With high organosolubility and flexibility, this synthetic strategy generated suitable precursors for subsequent polycondensation reactions. After polymerization, treatment with acid triggered the cleavage of the N-protecting groups. We hypothesize that the hydrogen bonding pattern generated along the polyaramide backbone could lead to the formation of a helical polymer. A drastic change in hydrodynamic volume was observed by gel permeation chromatography and dissolution in a chiral solvent lead to the observation of a circular dichroism signal for this polymer. The results of the polycondensations of N-protected oligobenzamides are reported herein. The formation of macrocycles as well as polymers could also be observed, giving a highly interesting insight into the underlying mechanism of the polycondensation of flexible, oligobenzamide-based oligomers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1731-1741 [ABSTRACT FROM AUTHOR]

A stereodivergent strategy enabled by bioinspired oxa-Michael cyclization was developed for the synthesis of functionalized tetrahydropyrans on the basis of the inherent symmetry in 1,3-diols, the symmetries of which were tunable by stereoselective hydroboration of an allene with a variety of alkylborane reagents and subsequent allylation of an aldehyde. The mechanism-based utilization of monoalkyl borane in the hydroboration and allylation cascade is unprecedented. [ABSTRACT FROM AUTHOR]

In chemical synthesis, rapid intramolecular rearrangements often foil attempts at site-selective bimolecular functionalization.We developed a microfluidic technique that outpaces the very rapid anionic Fries rearrangement to chemoselectively functionalize iodophenyl carbamates at the ortho position. Central to the technique is a chip microreactor of our design, which can deliver a reaction time in the submillisecond range even at cryogenic temperatures.The microreactorwas applied to the synthesis of afesal, a bioactive molecule exhibiting anthelmintic activity, to demonstrate its potential for practical synthesis and production. [ABSTRACT FROM AUTHOR]

A library of thirty novel thiazolo[5,4-f]quinazolin-9(8H)-one derivatives belonging to four series designated as 12, 13, 14 and 15 was efficiently prepared, helped by microwave-assisted technology when required. The efficient multistep synthesis of methyl 6-amino-2-cyano-benzo[d] thiazole-7-carboxylate (1) has been reinvestigated and performed on a multigram scale. The inhibitory potency of the final products against five kinases involved in Alzheimer's disease was evaluated. This study demonstrates that some molecules of the 12 and 13 series described in this paper are particularly promising for the development of new multi-target inhibitors of kinases. [ABSTRACT FROM AUTHOR]

Reactions of 5-alkyl- and 5-aryl-3 H-furan-2-ones with 1,3- and 1,4-binucleophiles of aromatic series were carried out for the first time under various conditions. In the presence of a base the reaction resulted in 1-R-1,3-dihydro-2 Н-pyrrol-2-ones, under milder conditions intermediates were isolated, 4-aryl-4-oxobutanamides. The structure of the latter was proved by spectral methods. By an example of 1-R-1,3-dihydro-2 Н-pyrrol-2-ones the possibility was demonstrated of their functionalization via introducing an aryldiazenyl fragment. [ABSTRACT FROM AUTHOR]

By alkylation of 4,4-disubstituted 2-(ethoxycarbonyl)butanolides new 4,4-disubstituted 2-alkenyl-2-(ethoxycarbonyl)butanolides were synthesized, which at alkaline hydrolysis formed 4,4-disubstituted 2-alkenylbutanolides. By oxidation of the latter with hydrogen peroxide and formic acid diololactones were obtained that in conditions of pinacol-pinacolone rearrangement and oxidation with lead tetraacetate afforded formyl- and epoxybutanolides of new structure. [ABSTRACT FROM AUTHOR]

Reaction was studied of 3,4-dihydroxyhexa-2,4-diene-1,6-dioic acid esters with 2,4-dinitrophenylhydrazine that led to the formation of esters of (3 E)-3-[2-(2,4-dinitrophenyl)-hydrazinylidene]-4-oxohexane-1,6-dioic and (3 E,4 E)-3,4-bis[2-(2,4-dinitrophenyl)hydrazinylidene]-hexane-1,6-dioic acids. The structural features of compounds synthesized were established from the data of IR and NMR spectra and X-ray diffraction (XRD) analysis. [ABSTRACT FROM AUTHOR]

4-Hydroxyphenylhydrazones of isatin derivatives were synthesized and oxidized with lead compounds to the corresponding azines. The introduction of isatin fragment in a quinoid system increases the redox potential of the system compared with 1,4-benzoquinone thus presumably resulting in the prevalence of 1,4-addition process. By an example of the reaction of N-methylisatins with hydrogen chloride it was shown that the reaction proceeded in keeping with the theoretically predicted direction. Azines, derivatives of isatin unsubstituted at the nitrogen atom, do not react with hydrogen chloride because of the presence of a strong intramolecular hydrogen bond. [ABSTRACT FROM AUTHOR]

By condensation of quinolin-5-amine with 5-arylfuran-2-carbaldehydes and cyclohexane-1,3-dione or dimedone new compounds were synthesized, 10,10-dimethyl-7-(5-arylfuran-2-yl)-9,10,11,12-tetrahydrobenzo[ b][1,7]phenanthrolin-8(7 H)-ones unsubstituted in the position 10. [ABSTRACT FROM AUTHOR]

Reaction of ethyl 6′,7′-dimethoxy-3′ Н-spiro[isoquinoline-1,4′-cyclopentane]-1′-carboxylate with ammonia and isopropylamine afforded dihydroisoquinoline carboxamides that were reduced with NaBH in amides of 6,7-dimethoxy-4-spirocyclopentane-1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid. The reaction of unsubstituted carboxamide with chloroacetyl chloride led to chloroamide that reacted with versatile secondary amines and heterylthiols providing the corresponding substituted amino- and sulfanylamides of tetrahydroisoquinoline series. [ABSTRACT FROM AUTHOR]

Proceeding from derivatives of levoglucosenone and piperilene Diels-Alder adduct a total chemical synthesis was completed of sarcodictyin A analog possessing a 14-methylcyclohex-12-ene ring А. A practical version was developed of N(τ)-methylation of urocanic acid. [ABSTRACT FROM AUTHOR]

Reactions of 4,6-dinitro-5,7-dichlorobenzofuroxane with substituted pyrimidines in aqueous DMSO proceed through an intermediate formation of 5-hydroxy-4,6-dinitro-7-chlorobenzofuroxane owing to the hydrolysis of one of the chlorine atoms with the subsequent formation of pyrimidine salts exhibiting a high biologic action. [ABSTRACT FROM AUTHOR]

Thiosemicarbazones of ketones from 3,6-diazahomoadamantane series were prepared by two procedures: by treating 3,6-diazahomoadamantan-9-ones with thiosemicarbazide and by a reaction of substituted (3,6-diazahomoadamantan-9-ylidene)hydrazines with versatile isothiocyanates. [ABSTRACT FROM AUTHOR]

The reaction of RSbO3H2 with t-butylsilanetriol has led to the isolation of organoantimony(v) based molecular triangles stabilized by siloxane frameworks. Depending on the reaction conditions employed or the substituents present on the antimony atom, either a combination of a disiloxane and a tetrasiloxane framework or a trisiloxane framework was generated in situ leading to the stabilization of the Sb3 triangle. [ABSTRACT FROM AUTHOR]

The sex pheromone of the endoparasitoid insect Xenos peckii (Strepsiptera: Xenidae) was recently identified as (7 E,11 E)-3,5,9,11-tetramethyl-7,11-tridecadienal. Herein we report the asymmetric synthesis of three candidate stereostructures for this pheromone using a synthetic strategy that relies on an sp3-sp2 Suzuki-Miyaura coupling to construct the correctly configured C7-alkene function. Comparison of 1H NMR spectra derived from the candidate stereostructures to that of the natural sex pheromone indicated a relative configuration of (3 R*,5 S*,9 R*). Chiral gas chromatographic (GC) analyses of these compounds supported an assignment of (3 R,5 S,9 R) for the natural product. Furthermore, in a 16-replicate field experiment, traps baited with the synthetic (3 R,5 S,9 R)-enantiomer alone or in combination with the (3 S,5 R,9 S)-enantiomer captured 23 and 18 X. peckii males, respectively (mean±SE: 1.4±0.33 and 1.1±0.39), whereas traps baited with the synthetic (3 S,5 R,9 S)-enantiomer or a solvent control yielded no captures of males. These strong field trapping data, in combination with spectroscopic and chiral GC data, unambiguously demonstrate that (3 R,5 S,9 R,7 E,11 E)-3,5,9,11-tetramethyl-7,11-tridecadienal is the X. peckii sex pheromone. [ABSTRACT FROM AUTHOR]

C-H functionalization has been established as a powerful strategy for the commercial construction of organic molecules. This review encompasses the most recent advances in C-H activation catalyzed by earth-abundant cobalt complexes, involving two types of fundamental reaction paths, that is, the concerted metalation--deprotonation (CMD) path associated with non-oxidative C-H activation and the intermolecular single-electrontransfer (SET) path. Transformations catalyzed by high-valent cobalt based on the two mechanisms and used in organic syntheses, including those involving C-C and C-X (X=O and N) bond formation, are herein presented. [ABSTRACT FROM AUTHOR]

A simple and efficient one-pot synthesis of enantiopure hexahydrofuro[2,3- b]furan-3-ol, a crucial component of HIV-1 protease inhibitors, was developed. The one-pot process involves an organocatalytic condensation followed by an enzymatic optical resolution. The condensation of 1,2-dihydrofuran and glycolaldehyde was achieved using Schreiner's thiourea catalyst (1 mol-%). A subsequent lipase-catalyzed kinetic resolution gave the target alcohol with >99 % ee. To demonstrate the practicality of this method, Darunavir, an HIV-1 protease inhibitor used to treat multi-drug-resistant HIV, was synthesized. [ABSTRACT FROM AUTHOR]

The syntheses of a tetracationic viologen and polycationic viologen dendrimers are described in this report. These water-soluble viologen dendrimers, the tetracationic viologen, and their DNA-containing complexes have been investigated by cyclic voltammetry (CV), electrophoresis, and atomic force microscopy with respect to their stability and effectiveness as possible transfection systems. The appearance of a negative potential shift and the loss of current in the cyclovoltammograms of viologen dendriplexes have been attributed to DNA/dendrimer complex formation. Oligomers of viologen with at least 4 positive charges are required for the formation of a primary DNA-viologen complex. The dynamics of the formation of a secondary complex was observed and studied by cyclic voltammetry. AFM measurements together with molecular modeling support the electrochemical results and show two different aggregates of the dendriplexes on gold. [ABSTRACT FROM AUTHOR]

Pentannulated heterocycles are the key structural subunit of many natural and biologically active compounds. Over the last decades, many precious metal-assisted pentannulations have been described as a consequence of an extensive research. This Focus Review gives an overview of precious metal-catalyzed reactions applied to the synthesis of cyclopenta-fused heterocycles in the last five years. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) are a class of zinc dependent endopeptidases which play a crucial role in a multitude of severe diseases such as cancer and osteoarthritis. We employed MMP-13 as the target enzyme for the structure-based design and synthesis of inhibitors able to recognize the catalytic zinc ion in addition to an allosteric binding site in order to increase the affinity of the ligand. Guided by molecular modeling, we optimized an initial allosteric inhibitor by addition of linker fragments and weak zinc binders for recognition of the catalytic center. Furthermore we improved the lipophilic ligand efficiency (LLE) of the initial inhibitor by adding appropriate zinc binding fragments to lower the clogP values of the inhibitors, while maintaining their potency. All synthesized inhibitors showed elevated affinity compared to the initial hit, also most of the novel inhibitors displayed better LLE. Derivatives with carboxylic acids as the zinc binding fragments turned out to be the most potent inhibitors (compound 3 (ZHAWOC5077): IC50 = 134 nM) whereas acyl sulfonamides showed the best lipophilic ligand efficiencies (compound 18 (ZHAWOC5135): LLE = 2.91). [ABSTRACT FROM AUTHOR]

The bottom-up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6Me}+ ( 1) is obtained by reacting [Zn2Cp*2] with [FeCp2][BAr4F] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower-nuclearity clusters {[Zn9](Cp*)6} ( 2) and {[Zn8](Cp*)5(tBuNC)3}+ ( 3). According to DFT calculations, 1 and 2 can be described as closed-shell species that are electron-deficient in terms of the Wade-Mingos rules because the apical ZnCp* units that constitute the cluster cage do not have three, but only one, frontier orbitals available for cluster bonding. Zinc behaves flexibly in building the skeletal metal-metal bonds, sometimes providing one major frontier orbital (like Group 11 metals) and sometimes providing three frontier orbitals (like Group 13 elements). [ABSTRACT FROM AUTHOR]

The first carbon tetrabromide-promoted novel double-oxidative dehydrogenative cyclization/acidic ring opening/aromatization tandem reaction of glycine derivatives with dioxane for the synthesis of complex quinoline motifs has been developed (up to 71% yield). The use of very inexpensive substrates (glycine derivatives and dioxane) and an extremely simple metal-free promoter (carbon tetrabromide) with green molecular oxygen (air) as an oxidant make this protocol very attractive for potential synthetic applications. A plausible mechanism involving a radical process is proposed. [ABSTRACT FROM AUTHOR]

A highly efficient protocol for the synthesis of pyrrolidones by the copper-catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids is discussed in this paper. A broad range of easily accessible alkynyl carboxylic acids were introduced at the β-methyl group of aliphatic amides with the assistance of an 8-aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic CN bond formation within one hour. High selectivity of β-methyl groups over methylene groups was observed, and the extension of this catalytic system to the activation of methylene CH bonds failed. The substrates with two different groups at the α-position of the aliphatic amides lead to the formation of diastereoisomers which is determined by 1H NMR spectroscopy. The initially produced products with Z-configurations can be easily transformed to the corresponding products with E-configurations by the treatment with dilute p-toluenesulfonic acid after the reaction. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 CH bonds. [ABSTRACT FROM AUTHOR]

The use of amidines for the tandem or one-pot synthesis of guanidines is reported. Guanidines are obtained by oxidative rearrangement of readily available and stable amidines into carbodiimides, followed by in situ reaction with amines. The protocol can be executed under mild reaction conditions (30 °C), in a green solvent (dimethyl carbonate). The amine scope is broad, including sterically hindered, oxidation-sensitive and chiral amines. Examples for the synthesis of both acyclic and cyclic guanidines are provided. 2-Propoxyphenyl iodide (2-PrOPhI) by-product, generated from the oxidant [ N-( p-toluenesulfonyl)imino](2-propoxyphenyl)iodinane (2-PrOPhINTs), can be isolated in high yields making regeneration of the hypervalent iodine reagent possible. The utility and greenness of the synthetic method versus the state-of-the-art is demonstrated by a new route towards the antihypertensive drug Pinacidil. The process mass intensity (PMI) of the new route is only 24% of the classical one. [ABSTRACT FROM AUTHOR]

Dibohemamines A-C ( 5- 7), three new dimeric bohemamine analogues dimerized through a methylene group, were isolated from a marine-derived Streptomyces spinoverrucosus. The structures determined by spectroscopic analysis were confirmed through the semi-synthetic derivatization of monomeric bohemamines and formaldehyde. These reactions, which could occur under mild conditions, together with the detection of formaldehyde in the culture, revealed that this dimerization is a non-enzymatic process. In addition to the unique dimerization of the dibohemamines, dibohemamines B and C were found to have n m cytotoxicity against the non-small cell-lung cancer cell line A549. In view of the potent cytotoxicity of compounds 6 and 7, a small library of bohemamine analogues was generated for biological evaluation by utilizing a series of aryl and alkyl aldehydes. [ABSTRACT FROM AUTHOR]

A catalytic system consisting of 5 mol% CoCl2 and 10 mol% isoquinoline allows a convenient cross-coupling of benzylic zinc reagents with various aryl and heteroaryl bromides or chlorides leading to polyfunctionalized diaryl- and aryl-heteroaryl-methane derivatives. [ABSTRACT FROM AUTHOR]

A mini library of HDAC inhibitors with peptoid-based cap groups was synthesized using an efficient multicomponent approach. Four compounds were identified as potent HDAC6 inhibitors with a selectivity over other HDAC isoforms. The most potent HDAC6 inhibitor revealed remarkable chemosensitizing properties and completely reverted the cisplatin resistance in Cal27 CisR cells. [ABSTRACT FROM AUTHOR]

Two new isomorphous polyhedron-based MOFs (JLU-Liu20 and JLU-Liu21), with dual functionalities of OMSs and LBSs, have been synthesized by using the SBB strategy. By judiciously avoiding the DABCO axial ligand, JLU-Liu21 possesses more OMSs than JLU-Liu20, and exhibits a significant enhancement of CO2 uptake capacity 210 versus 162 cm3 g−1 for JLU-Liu20 at 273 K under 1 bar. [ABSTRACT FROM AUTHOR]

Four novel Anderson-type polyoxometalates (POMs) [TeMo6O24]6− (TeMo6)-based metal–organic complexes (MOCs), namely, H2[Zn4(3-Hdpyp)2(TeMo6O24)2(H2O)16]·6H2O (1), [Zn3(3-dpyb)2(TeMo6O24)(H2O)12]·8H2O (2), [Cu2(4-Hdpyp)2(TeMo6O24)(H2O)6]·4H2O (3), and [Cu3(3-dpyp)2(TeMo6O24)(H2O)8]·4H2O (4) (3-dpyp = N,N′-bis(3-pyridinecarboxamide)-1,3-propane, 3-dpyb = N,N′-bis(3-pyridinecarboxamide)-1,4-butane, 4-dpyp = N,N′-bis(4-pyridinecarboxamide)-1,3-propane), were hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). In complex 1, two TeMo6 polyoxoanions bridge ZnII ions to generate a discrete tetranuclear zinc complex H2[Zn4(3-Hdpyp)2(TeMo6O24)2(H2O)16]. In 2, the TeMo6 anions connect the metal–organic units [Zn3(3-dpyb)2]6+ to form an Anderson-type TeMo6-based wave-like metal–organic chain. Both the discrete tetranuclear subunits in 1 and 1D wavy chains in 2 were further extended to 2D supramolecular networks through the hydrogen bonding interactions. In complex 3, the TeMo6 anions link the metal–organic units [Cu2(4-Hdpyp)2]6+ to construct a 2D layer, which is further extended to a 3D supramolecular framework by the hydrogen bonding interactions. In complex 4, the TeMo6 polyoxoanions bridge the CuII ions to generate a 2D Cu-TeMo6 inorganic layer, which is further linked by the μ2-bridging 3-dpyp ligands to form a 3D metal–organic framework. The effects of various coordination modes of TeMo6 polyanions and the bis-pyridyl-bis-amide ligands, as well as the central metals on the structures of the title complexes have been discussed. Besides, the fluorescence, electrochemical properties and photocatalytic activities of the title complexes have been investigated in detail. [ABSTRACT FROM AUTHOR]

Cu3(BTC)2 is an efficient and reusable heterogeneous catalyst for the dehydrogenative coupling of silanes with alcohols. Activity data and CO adsorption suggest that Cu(ii) and in situ generated Cu(i) are the active species. Other MOFs such as Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are unable to promote this cross-coupling. [ABSTRACT FROM AUTHOR]

Tetrasiladigermatricyclohexanes in two isomeric forms (chair and doubly-bridged tetrahedron) are obtained by the reaction of MeLi with an α-chlorosilyl functionalized NHC-stabilized silagermenylidene. 29Si NMR at low temperature proves the initial formation of a monomeric NHC-adduct of a disilenyl germylene followed by cyclisation to the isomeric heavy cyclopropene. Addition of an excess of NHC stabilizes the both intermediates and demonstrates the reversibility of rate-determining initial equilibria involving NHC dissociation. Finally, a mixture of two isomeric tricyclic Si4Ge2 species is obtained: at elevated temperature the chair isomer converts to the doubly edge-bridged tetrahedron. [ABSTRACT FROM AUTHOR]

A new 3D porous anionic MOF (AMOF-1) based on ZnII and a flexible tetracarboxylate linker has been synthesized. AMOF-1 showed potential for capture and removal of toxic metal ions from aqueous solution with a detection limit in the ppm level. The CuII@AMOF-1′ hybrid obtained by post-synthetic metalation is studied as a heterogeneous catalyst for the synthesis of benzimidazole derivatives. [ABSTRACT FROM AUTHOR]

A multi-stimuli responsive small molecule organic material has been developed, which for the first time exhibits dual-wavelength response to render photocoloration under visible light and turn-on luminescence under UV light. The colored product can be bleached and shows turn-on luminescence again when re-exposed to UV light. [ABSTRACT FROM AUTHOR]

A new synthesis of bis(acyl)phosphane oxide (BAPO) photoinitiators was developed which can be used to functionalize cellulose nanocrystal surfaces for polymer grafting. Hybrid materials with excellent graft yields can be rapidly obtained under mild and acid-free conditions. [ABSTRACT FROM AUTHOR]

Cu3(BTC)2 is an efficient and reusable heterogeneous catalyst for the dehydrogenative coupling of silanes with alcohols. Activity data and CO adsorption suggest that Cu(ii) and in situ generated Cu(i) are the active species. Other MOFs such as Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are unable to promote this cross-coupling. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles in anatase and rutile forms was characterized and studied by several techniques including X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and successfully applied as an efficient and heterogeneous catalyst in the synthesis of 1,8-dioxo-decahydroacridines via the one-pot multi-component condensation reaction of dimedone with aromatic aldehydes and ammonium acetate or aromatic amines under mild and solvent-free conditions. [ABSTRACT FROM AUTHOR]

Anthraquinone based anion receptors have gained importance due to their colorimetric response on sensing a specific anion and the possibility of tuning this property by varying the conjugated moiety (the donor) to the diamine. In this work, we have synthesized and characterized four anthraimidazoledione compounds having 2,5-dihydroxy benzene, 4-(bis(2-chloroethyl)amino)benzene, imidazole and 4-methylthiazole moieties respectively (1–4). All of them were probed for their potential as anion sensors to study the effect of changes in the hydrogen bond donor–acceptor. The p-hydroquinone bound anthraimidazoledione (1) and thioimidazole bound anthraimidazoledione (4) were able to detect both F− and CN− in the presence of other anions Cl−, Br−, I−, H2PO4−, OAc−, NO3− and ClO4−. Both 1 and 4 could not differentiate F− from CN− and provided a similar response to both. The 1H NMR studies of 1 and 4 with F−, showed the formation of [HF2]− at 16.3 ppm and the 19F NMR showed a sharp peak at −145 ppm in both cases. However, although there may be NMR evidence of [HF2]− formation F− may not be detected colorimetrically if the CT band remains almost unchanged, as found for 3. The results emphasize that the change of a hetero atom in the donor moiety of an anthraimidazoledione may render a large difference in sensitivity. In the case of 4 selective detection of F− was possible in the presence of 0.5 equivalent of Cu2+ with the exhibition of a distinct green colour with a Δλ shift of ca. 50 nm in contrast to CN− which showed orange colouration with a Δλ shift of only 15 nm. In the presence of Cu2+ the F− detection limit was 0.038(5) ppm (below the WHO specified level) at a receptor concentration of 25 μM. [ABSTRACT FROM AUTHOR]

We report herein the synthesis of the first structurally characterized homoleptic actinide aryl complexes, [Li(DME)3]2[Th(C6H5)6] (1) and [Li(THF)(12-crown-4)]2[Th(C6H5)6] (2), which feature an anion possessing a regular octahedral (1) or a severely distorted octahedral (2) geometry. The solid-state structure of 2 suggests the presence of pseudo-agostic ortho C–H…Th interactions, which arise from σ(C–H) → Th(5f) donation. The non-octahedral structure is also favoured in solution at low temperatures. [ABSTRACT FROM AUTHOR]