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The Sharpless asymmetric dihydroxylation (AD) finds widespread use in natural product and drug molecule syntheses, in part, due to its efficiency and predictability. However, the tandem AD of dienes is much less studied, but important in complex molecular synthesis. Herein, a biologically relevant tandem AD is reported, and several anomalies are discovered with the accepted model. These include the formation of unpredicted diastereoisomers, with matched and mismatched stereocenters contradicting the Sharpless mnemonic device. From a structural analysis of the tandem AD, we present a strategy to improve asymmetric induction in sterically hindered alkenes using double diastereodifferentiation from a 9‐bond distant stereocenter. A theoretical justification for the unpredicted stereoselectivity, accounting for the influence of steric hindrance and pre‐installed chirality, is proposed. [ABSTRACT FROM AUTHOR]

(NH4)2[Zn2(O3PCH2CH2COO)2]⋅5 H2O (BIRM‐1) is a new metal phosphonate material, synthesized through a simple hydrothermal reaction between zinc nitrate and 3‐phosphonopropionic acid, using urea and tetraethylammonium bromide as the reaction medium. In common with other metal–organic framework materials, BIRM‐1 has a large three‐dimensional porous structure providing potential access to a high internal surface area. Unlike most others, it has the advantage of containing ammonium cations within the pores and has the ability to undergo cation exchange. Additionally, BIRM‐1 also exhibits a reversible dehydration behavior involving an amorphization‐recrystallization cycle. The ability to undergo ion exchange and dynamic structural behavior are of interest in their own right, but also increase the range of potential applications for this material. Here the crystal structure of this new metal phosphonate and its ion exchange behavior with K+ as an exemplar are studied in detail, and its unusual structure‐reviving property reported. [ABSTRACT FROM AUTHOR]

The study of organosulfates is a burgeoning area in biology, yet there are significant challenges with their synthesis. We report the development of a tributylsulfoammonium betaine as a high yielding route to organosulfates. The optimised reaction conditions were interrogated with a diverse range of alcohols, including natural products and amino acids. [ABSTRACT FROM AUTHOR]

Metal‐organic cages (MOCs) are popular host architectures assembled from ligands and metal ions/nodes. Assembling structurally complex, low‐symmetry MOCs with anisotropic cavities can be limited by the formation of statistical isomer libraries. We set out to investigate the use of primary coordination‐sphere engineering (CSE) to bias isomer selectivity within homo‐ and heteroleptic PdnL2n cages. Unexpected differences in selectivities between alternative donor groups led us to recognise the significant impact of the second coordination sphere on isomer stabilities. From this, molecular‐level insight into the origins of selectivity between cis and trans diastereoisomers was gained, highlighting the importance of both host–guest and host‐solvent interactions, in addition to ligand design. This detailed understanding allows precision engineering of low‐symmetry MOC assemblies without wholesale redesign of the ligand framework, and fundamentally provides a theoretical scaffold for the development of stimuli‐responsive, shape‐shifting MOCs. [ABSTRACT FROM AUTHOR]

Metal‐organic cages (MOCs) are popular host architectures assembled from ligands and metal ions/nodes. Assembling structurally complex, low‐symmetry MOCs with anisotropic cavities can be limited by the formation of statistical isomer libraries. We set out to investigate the use of primary coordination‐sphere engineering (CSE) to bias isomer selectivity within homo‐ and heteroleptic PdnL2n cages. Unexpected differences in selectivities between alternative donor groups led us to recognise the significant impact of the second coordination sphere on isomer stabilities. From this, molecular‐level insight into the origins of selectivity between cis and trans diastereoisomers was gained, highlighting the importance of both host–guest and host‐solvent interactions, in addition to ligand design. This detailed understanding allows precision engineering of low‐symmetry MOC assemblies without wholesale redesign of the ligand framework, and fundamentally provides a theoretical scaffold for the development of stimuli‐responsive, shape‐shifting MOCs. [ABSTRACT FROM AUTHOR]

Four novel bis-boronic acid compounds were synthesised via copper catalysed azide–alkyne cycloaddition (CuAAC) reactions. Glucose selectivity was observed for a particular structural motif. Moreover, a new glucose selective fluorescent sensor was designed and synthesised as a result. [ABSTRACT FROM AUTHOR]

Synthetic strategies towards molecular dyads based on peri-substituted dichalcogenide (S,Se) [FeFe]-hydrogenase synthetic mimics covalently linked to a ZnTPP photosensitizer are described. Dithiolate and diselenolate model systems 2- 5 are prepared through condensation of 2-naphthaldehydes with p-methoxyaniline, reduction of the resulting Schiff base and oxidative insertion of Fe2(CO)6 into the dichalcogen bond of the imine or amine. Diselenolate-based [FeFe] complexes (imine 3 and amine 5) are more efficient in electrocatalysis of proton reduction than their sulfur analogues 2 and 4 with increasing concentrations of pTsOH. Molecular dyad 1 containing a peri-substituted naphthalene dithiolate Fe2(CO)6 cluster covalently linked via an amine to ZnTPP is prepared through sequential zinc insertion into the porphyrin followed by iron insertion into the disulfide bond. [ABSTRACT FROM AUTHOR]

Eightdithiolato-, diselenolato-, and mixed S,Se-Fe2(CO)6complexes based on peri-substitutednaphthalene and phenanthrene dichalcogenides are prepared by oxidativeinsertion of Fe3(CO)12into the dichalcogenbonds of 2,7-dimethoxynaphtho[1,8-cd][1,2]dithiole,three naphtho[1,8-cd][1,2]diselenoles, two naphtho[1,8-cd][1,2]thiaselenoles, phenanthro[1,10-cd][1,2]dithiole, and phenanthro[1,10-cd][1,2]diselenole.Complexes are characterized by 1H, 13C NMR,UV/vis, and IR spectroscopy and by X-ray analysis. The effect of replacingsulfur with selenium, incorporating electron-donating groups (2,7-di-tert-butyl, 2,7-dimethoxy) on the naphthalene ring system,and changing the degree of conjugation in the aromatic backbone (naphthalenevs phenanthrene) on the reduction potential is evaluated by cyclicvoltammetry. The electrocatalytic activity of these [FeFe]-hydrogenasesynthetic mimics for proton reduction in the presence of increasingconcentrations of p-TsOH is investigated. Diselenolate-based[FeFe]-complexes show enhanced catalytic activity for proton reductioncompared with their sulfur congeners. [ABSTRACT FROM AUTHOR]

In an approach to the biologically important 6-azabicyclo[3.2.1]octane ring system, the scope of the tandem 4- exo-trig carbamoyl radical cyclization-dithiocarbamate group transfer reaction to ring-fused β-lactams is evaluated. β-Lactams fused to five-, six-, and seven-membered rings are prepared in good to excellent yield, and with moderate to complete control at the newly formed dithiocarbamate stereocentre. No cyclization is observed with an additional methyl substituent on the terminus of the double bond. Elimination of the dithiocarbamate group gives α,β- or β,γ-unsaturated lactams depending on both the methodology employed (base-mediated or thermal) and the nature of the carbocycle fused to the β-lactam. Fused β-lactam diols, obtained from catalytic OsO4-mediated dihydroxylation of α,β-unsaturated β-lactams, undergo semipinacol rearrangement via the corresponding cyclic sulfite or phosphorane to give keto-bridged bicyclic amides by exclusive N-acyl group migration. A monocyclic β-lactam diol undergoes Appel reaction at a primary alcohol in preference to semipinacol rearrangement. Preliminary investigations into the chemo- and stereoselective manipulation of the two carbonyl groups present in a representative 7,8-dioxo-6-azabicyclo[3.2.1]octane rearrangement product are also reported. [ABSTRACT FROM AUTHOR]

We report the structures of three new materials in the MDABCO-based perovskite family. Analysis of the Goldschmidt tolerance factor and octahedral factor enable us to propose compositional limits for pseudo-cubic perovskite phase formation and suggest directions for further materials discovery in this family of new ferroelectrics. [ABSTRACT FROM AUTHOR]

Cyclic voltammetry readily visualizes the redox properties of many proteins. Net electron exchange between the protein and an electrode produces an electrical current that simultaneously quantitates and characterizes the underlying redox event(s). However, no direct information regarding the molecular origin, or consequences, of electron transfer is available. Integrating voltammetric and spectroscopic methods is one route to a more ‘holistic’ description of protein electron transfer. Here, we illustrate this approach with spectroelectrochemical studies of Rhodovulum sulfidophilum cytochrome c 2 and Escherichia coli cytochrome bd that employ electronic absorbance, infra-red and magnetic circular dichroism spectroscopies. [ABSTRACT FROM AUTHOR]

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus‐containing analogues of triazenes are underexplored but offer great potential as flexible and small bite‐angle ligands. This manuscript explores the synthesis and characterisation of a family of air‐stable azophosphine‐borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues. [ABSTRACT FROM AUTHOR]

The regiodivergent synthesis of 4‐ and 5‐sulfenyl oxazoles from 1,4,2‐dioxazoles and alkynyl thioethers has been achieved. Gold‐catalysed conditions are used to favour the formation of 5‐sulfenyl oxazoles via β‐selective attack of the nitrenoid relative to the sulfenyl group. In contrast, 4‐sulfenyl oxazoles are formed by α‐selective reaction under Brønsted acid conditions from the same substrates. The nature of stabilising gold‐sulfur interactions have been investigated by natural bond orbital analysis, showing that the S→Au interactions are significantly stronger in the intermediate that favours the 5‐sulfenyl oxazoles. A kinetic survey identifies catalyst inhibition processes. This study into the regiodivergent methods includes the development of telescoped annulation‐oxidation protocols for regioselective access to oxazole sulfoxides and sulfones. [ABSTRACT FROM AUTHOR]

The [2,3]-sigmatropic rearrangement of sulfonium ylides bearing substituted allyl groups creates two contiguous stereocentres. Low diastereoselectivity is typically observed from commonly used α-diazocarboxylic ester precursors. High diastereoselectivity was previously revealed in a gold-catalyzed multicomponent route into allyl sulfonium ylides by reaction of ynamide, oxidant and allyl sulfides. The effect of substrate modifications on the diastereoselectivity have been studied, with N -phenyl methanesulfonamide derived ynamides proving the most effective. This report includes an enhanced experimental procedure, and a demonstration that the gold-catalyzed process remains highly effective at −78 °C. Image 1 [ABSTRACT FROM AUTHOR]

Dual detection systems are of interest for rapid, accurate data collection in sensing systems and in vitro testing. We introduce an IrIII complex with a boronic acid receptor site attached to the 2‐phenylpyridine ligand as an ideal probe with photo‐ and electrochemical signals that is sensitive to monosaccharide binding in aqueous solution. The complex displays orange luminescence at 618 nm, which is reduced by 70 and 40 % upon binding of fructose and glucose, respectively. The electro‐chemiluminescent signal of the complex also shows a direct response to monosaccharide binding. The IrIII complex shows the same response upon incorporation into hydrogel matrices as in solution, thus demonstrating the potential of its integration into a device, as a nontoxic, simple‐to‐use tool to observe sugar binding over physiologically relevant pH ranges and saccharide concentrations. Moreover, the complex's luminescence is responsive to monosaccharide presence in cancer cells. [ABSTRACT FROM AUTHOR]

A versatile route to 1,2,5-trisubstituded γ-lactams with tertiary alcohol functionality at the 3-position, from homoallylic amine derivatives with a methyl group at the β-position, is presented. [ABSTRACT FROM AUTHOR]

In an approach to the biologically important 6-azabicyclo[3.2.1]octane ring system, the scope of tandem 4-exo-trig carbamoyl radical cyclization-dithiocarbamate group transfer reaction to ring-fused β-lactams is evaluated. [ABSTRACT FROM AUTHOR]

Michael addition of a proline-derived triketopiperazine (TKP) to β-substituted enones and acrylamides, mediated by a cinchona alkaloid catalyst, delivers products possessing a bicyclo[2.2.2]diazaoctane structure in high yield and enantiomeric ratio (er). Further modification of the amide products toward polycyclic scaffolds resembling members of the prenylated alkaloid family is also demonstrated. [ABSTRACT FROM AUTHOR]

The dolabellane‐type diterpene dictyoxetane represents a significant challenge to synthetic organic chemistry. Methodology directed towards the total synthesis of naturally occurring (+)‐dictyoxetane is reported. Catalytic asymmetric synthesis of the trans‐hydrindane ring system is achieved through chemoselective deoxygenation of the Hajos‐Parrish ketone. An alternative to the Garst‐Spencer furan annulation is developed for the synthesis of a 2,5‐dimethyl, tetrasubstituted furan, employing a tandem 5‐exo‐dig alcohol to alkyne cyclisation/aromatisation reaction as a key step. The (4+3) cycloaddition reaction of an oxyallyl cation with a tetrasubstituted furan is established on a cyclohexanone‐derived model system, and a range of related (4+3) cycloadditions investigated on a homochiral, trans‐hydrindane‐fused furan, where regio‐ and diastereoselectivity is required for the natural product synthesis. In an alternative (4+2) Diels‐Alder approach, a C2‐symmetric vinyl sulfoxide‐based chiral ketene equivalent is used to prepare oxanorbornenes with the same oxygen bridge stereochemistry found in the 2,7‐dioxatricyclo[4.2.1.03,8]nonane ring system of the natural product. [ABSTRACT FROM AUTHOR]

Herein, a library of trifluoroethyl substituted aminomaleimide derivatives are reported with small size and enhanced emissions in both solution and solid‐state. A diCH2CF3 substituted aminochloromaleimide exhibits the most efficient dual‐state emission (Φf >50 % in solution and solid‐state), with reduced quenching from protic solvents. This is attributed to the reduction of electron density on the maleimide ring and suppressed π‐π stacking in the solid‐state. This mechanism was explored in‐depth by crystallographic analysis, and modelling of the electronic distribution of HOMO‐LUMO isosurfaces and NCI plots. Hence, these dual‐state dyes overcome the limitations of single‐state luminescence and will serve as an important step forward for this rapidly developing nascent field. [ABSTRACT FROM AUTHOR]

The interaction of salphen-type NiII, CuII and ZnII complexes with native DNA was investigated by exploiting linear dichroism experiments. The NiII complex behaves as a typical intercalator, binding strongly and stiffening and unwinding the DNA. The strength of the DNA interaction is slightly weaker for the copper complex and much weaker for the zinc complex. Plasmid-DNA gel electrophoresis experiments indicated that while CuII and ZnII complexes do not induce the unwinding of supercoiled DNA, the NiII complex has a nuclease activity without the addition of external agents. On the other hand, as shown in the PCR assays, we demonstrate that, at the used concentrations, only the CuII complex is able to inhibit the DNA amplification mediated by Taq DNA polymerase. In this paper we have also reported a detailed characterization of the three compounds including 2D-NMR and ESI-mass experiments and X-ray single crystal structure of the copper and nickel compounds. [ABSTRACT FROM AUTHOR]

The powerful hydrogen bonding capabilityof adenine makes it akey component of the DNA double helix, while as a crystalline molecularmaterial, these hydrogen bond donors and acceptors make it a goodpotential cocrystal component possessing distinct physical properties.Here, we report the preparation and structure determination of fouradenine-based multicomponent adducts formed with a number of dicarboxylicacids: an anhydrous cocrystal with succinic acid (1),anhydrous salts with fumaric acid (2) and maleic acid(3), and a methanolated salt with maleic acid (4). The supramolecular behavior of adenine in these materialsis discussed in terms of strong hydrogen-bonded bidentate motifs formedbetween the adenine and acid components and the homomeric adeninesynthons retained in these structures. The additional formation ofa CH···N interaction on the Watson–Crick sitein (3) enables the stabilization of the unusual 3H,7Hadeninium tautomer within a purelymolecular material. [ABSTRACT FROM AUTHOR]

Examines the folding pathway of kinase. Classic up-down four-helical bundle formed by the FK506-FKBP12 binding-domain of the kinase; Folding rate constant; Equilibrium denaturation.

Carbazoles are widely exploited for their interesting photophysical and electronic properties, however bay (4,5-) functionalization is challenging, and previously inaccessible through carbazole C–H activation. We report a simple methodology which introduces a range of versatile 4,5-functionality, enabling the wider investigation of ring annulation and close proximity effects on carbazole properties. [ABSTRACT FROM AUTHOR]

Parthenolide exhibits anti-leukaemia activity, whilst its synthetic modification to impart improve drug-like properties, including 1,4-conjugate addition of primary and secondary amines, have previously been used, 1,4-addition of aniline derivatives to parthenolide has not been fully explored. A protocol for such additions to parthenolide is outlined herein. Reaction conditions were determined using tulipane as a model Michael acceptor. Subsequently, aniline-containing parthenolide derivatives were prepared under the optimised conditions and single crystal X-ray diffraction structures were resolved for three of the compounds synthesised. The synthesised derivatives, along with compounds resulting from a side reaction, were tested for their in vitro anti-leukaemia activity using the chronic lymphocytic leukaemia (CLL) MEC1 cell line. Computational studies with the 2RAM protein structure suggested that the activity of the derivatives was independent of their in silico ability to dock with the Cys38 residue of NF-κB. Image 1 • Squaric acid-catalysed 1,4-conjugate addition of aniline derivatives to parthenolide. • Anti-chronic lymphocytic leukaemic activity. • Crystal structures of some products and by-products. [ABSTRACT FROM AUTHOR]

Three new fumaramide-derived [3]rotaxanes have been synthesized, with the aim of macrocycle linking to form a molecular box. In one case, a nine-component templated [3]rotaxane synthesis was accomplished in 40% yield. Rotaxane reduction resulted in an unexpectedly facile de-slipping process. [ABSTRACT FROM AUTHOR]

A new chiral organometallic nucleoside analogue containing ruthenocene is reported, in which alkylthymine and alkylhydroxyl groups are attached in adjacent positions on one cyclopentadienyl ring. The synthetic procedures for this metallocene derivative and two control compounds are described, along with their characterisation by cyclic voltammetry and X-ray crystallography. Their biological activities in a human pancreatic cancer cell line (MIA-Pa-Ca-2) were significantly lower than those of three previously reported analogous ferrocene compounds, indicating that the choice of metallocene metal atom (Fe or Ru) plays a pivotal role in determining the anticancer properties of these nucleoside analogues, which in turn suggests a different mode of action from that of a conventional nucleoside analogue. [ABSTRACT FROM AUTHOR]

A new series of chiral ferrocene derivatives containing both a hydroxyalkyl group and a thyminyl group on one cyclopentadienyl ring have been synthesised to probe structure-activity relationships in cancer cell line cytotoxicities. The stereoisomers of enantiomeric pairs of these so-called ferronucleosides have been studied and characterised by a combination of chiral analytical HPLC and single-crystal X-ray diffraction. Biological activity studies revealed that changing the length of the hydroxyalkyl group had marked effects on IC50 values, with compounds having shorter arms that more closely resemble endogenous nucleosides exhibiting lower cytotoxicities. The lipophilicities and electrochemical properties of this compound series have been studied to rationalise these trends and indicate future directions of study. [ABSTRACT FROM AUTHOR]

A doubly pyrene-grafted bis-cyclometallated iridium complex with engineered electronically excited states demonstrates reversible electronic energy transfer between adjacent chromophores giving rise to extremely long-lived red luminescence in solution (τ = 480 μs). Time-resolved spectroscopic studies afforded determination of pertinent photophysical parameters including rates of energy transfer and energy distribution between constituent chromophores in the equilibrated excited molecule (ca. 98% on the organic chromophores). Incorporation into a nanostructured metal–oxide matrix (AP200/19) gave highly sensitive O2 sensing films, as the detection sensitivity was 200–300% higher than with the commonly used PtTFPP and approaches the sensitivity of the best O2-sensing dyes reported to date. [ABSTRACT FROM AUTHOR]

The regioselective gold-catalysed hydration of propargylic alcohols to β-hydroxy ketones can be achieved by diverting the gold-catalysed Meyer-Schuster rearrangement through the addition of a protic additive with a p Ka of 7-9 such as p-nitrophenol, boric acid or a boronic acid. This provides an interesting alternative to an aldol reaction when combined with the straightforward addition of an alkyne to an aldehyde or ketone. The gold-catalysed reaction of an electron-deficient, sterically hindered propargylic alcohol with a boronic acid led to the formation of an unusually stable cyclic boron enolate. [ABSTRACT FROM AUTHOR]

Blue- and green-emitting cyclometalated liquid-crystalline iridium complexes are realized by using a modular strategy based on strongly mesogenic groups attached to an acetylacetonate ancillary ligand. The cyclometalated ligand dictates the photophysical properties of the materials, which are identical to those of the parent complexes. High hole mobilities, up to 0.004 cm2 V−1 s−1, were achieved after thermal annealing, while amorphous materials show hole mobilities of only approximately 10−7-10−6 cm2 V−1 s−1, similar to simple iridium complexes. The design strategy allows the facile preparation of phosphorescent liquid-crystalline complexes with fine-tuned photophysical properties. [ABSTRACT FROM AUTHOR]

Crystal structures of six 1 : 1 triiodide salts of a series of enantiopure bis(pyrrolo[3,4-d])TTF derivatives, the first structures of radical cation salts reported for this bis(pyrrolo) donor system, show three different arrangements of triiodide ions, organised either in head-to-tail pairs, in infinite lines, or in a castellated arrangement. The complex crystal structures, obtained by electrocrystallisation, are influenced by the presence of solvent, for example changing an ABCABC packing arrangement to ABAB with inclusion of THF, as well as by the size of the chiral side chain. [ABSTRACT FROM AUTHOR]

The title compound, 5,5′-bis­(tri­methyl­silyl­ethynyl)-2,2′-bi­pyridine, C20H24N2Si2, is a tri­methyl­silyl-protected dialkyne. It is a precursor in the preparation of platinum di-yne complexes and platinum poly-yne polymers. Such organic compounds are of interest because of the extended π-conjugation that occurs through the hetero-aromatic linker unit in the molecular backbone. Within the mol­ecule, the ­silyl-alkyne groups are essentially linear and the bi­pyridine unit is approximately planar with a dihedral angle of 5.3 (1)° between the planes. [ABSTRACT FROM AUTHOR]

Michael addition reactions of triketopiperazine derivatives to enones catalyzed by a cinchona alkaloid-derived catalyst are studied. [ABSTRACT FROM AUTHOR]

A new series of chiral ureas containing one or two redox-active ferrocene units was synthesised and studied in order to investigate the effect of planar chirality and central chirality on electrochemical chiral sensing. Binding of chiral carboxylate anions in organic solvents through H-bond formation caused a negative shift in the potentials of the ferrocene/ferrocenium (Fc/Fc+) couples of the receptors, demonstrating their use as electrochemical sensors in solution. While the presence of two ferrocene units gave no marked improvement in the chiral sensing capabilities of these systems, the introduction of planar chirality, in addition to central chirality, switched the enantiomeric binding preference of the system and also caused an interesting change in the appearance of some voltammograms, with unusual two-wave behaviour observed upon binding a protected prolinate guest. [ABSTRACT FROM AUTHOR]

Crystals of Ph[sub 3]SnCl (1) were grown from a methanol/acetonitrile solution. Compounds [Ph[sub 3]SnOH][sub n ] (2) and [(Ph[sub 2]Sn)[sub 4]Cl[sub 2]O[sub 2](OH)[sub 2]] (3) were crystallized from diethyl ether/methanol/acetonitrile and hot acetone/water solutions respectively, of the white precipitation, formed by adding KOH to solutions of 1 and [Ph[sub 2]SnCl[sub 2]] in 1 : 1 and 1 : 2 molar ratios respectively. Complex 1 was characterized by X-ray crystallography. X-ray structure determination of compounds 2 and 3 confirmed the previously reported identities. The molecular structure of 1, reported here, is a new polymorphic form of the known one for Ph[sub 3]SnCl. Four independent [Ph[sub 3]SnCl] molecules constitute the crystal structure of 1. The moieties are packed in two pairs in a tail-to-tail arrangement. Complexes 1-3 were evaluated for their in vitro cytotoxic activity (cell viability) against human cancer cell lines: HeLa (human cervical), MCF-7 (breast, estrogen receptor (ER) positive), MDA-MB-231 (breast, ER negative), A549 (lung), Caki-1 (kidney carcinoma), 786-O (renal adenocarcinoma), K1 (thyroid carcinoma), and the normal human lung cell line MRC-5 (normal human fetal lung fibroblast cells) versus, the normal immortalized human mammary gland epithelial cell line MTSV17 with a sulforhodamine B (SRB) assay. The results show potent cytotoxic activity of the complexes against all cell lines used, which was superior to that of cisplatin (CDDP). Compounds 1-3 showed higher activity against breast cancer cells MCF-7 (ER positive) than against of MDA-MB-231 (ER negative). These findings prompted us to search for possible interaction of these complexes with other cellular elements of fundamental importance in cell proliferation. The influence of these complexes 1-3 upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX), as well as their binding affinity towards calf thymus-DNA, were kinetically and theoretically studied. The organotin compounds [Ph[sub 3]SnCl] (1), [Ph[sub 3]SnOH][sub n] (2), and [(Ph[sub 2]Sn)[sub 4]Cl[sub 2]O[sub 2](OH)[sub 2]] (3) were evaluated for their binding properties towards lipoxygenase (LOX) and calf thymus-DNA and the results are compared with their in vitro cytotoxicity against a panel of cancer cell lines. Compounds 1 and 2 showed selective cytotoxic activity against carcinoma cells, especially against MCF-7 (human breast adenocarcinoma) cells. [ABSTRACT FROM AUTHOR]

This radical cascade reaction initiated from sulfur-substituted diketopiperazine (I) affords indolines as key stepping stones to avrainvillamide, stephacidin B, and their bioactive analogues. [ABSTRACT FROM AUTHOR]

A series of trimethylsilyl-protected di-alkynes incorporating 3,4-ethylenedioxythiophene (EDOT) linker groups Me3Si–CC–R–CC–SiMe3(R = ethylenedioxythiophene-3,4-diyl 1a, 2,2′-bis-3,4-ethylenedioxythiophene-5,5′-diyl 2a, 2,2′,5′,2′′-ter-3,4-ethylenedioxythiophene-5,5′′-diyl 3a) and the corresponding terminal di-alkynes, H–CC–R–CC–H 1b–2bhas been synthesized and characterized and the single crystal X-ray structure of 1ahas been determined. CuI-catalyzed dehydrohalogenation reaction between trans-[(Ph)(Et3P)2PtCl] and the terminal di-alkynes 1b–2bin iPr2NH/CH2Cl2(2 : 1 mole ratio) gives the Pt(ii) di-ynes trans-[(Et3P)2(Ph)Pt–CC–R–CC–Pt(Ph)(Et3P)2] 1M–2Mwhile the dehydrohalogenation polycondensation reaction between trans-[(nBu3P)2PtCl2] and 1b–2b(1 : 1 mole ratio) under similar reaction conditions affords the Pt(ii) poly-ynes trans-[Pt(PnBu3)2–CC–R–CC-]n1P–2P. The di-ynes and poly-ynes have been characterized spectroscopically and, for 1Mand 2M, by single-crystal X-ray which confirms the “rigid rod” di-yne backbone. The materials possess excellent thermal stability, are soluble in common organic solvents and readily cast into thin films. Optical absorption spectroscopic measurements reveal that the EDOT spacers create stronger donor-acceptor interactions between the platinum(ii) centres and conjugated ligands along the rigid backbone of the organometallic polymers compared to the related non-fused and fused oligothiophene spacers. [ABSTRACT FROM AUTHOR]

Three peri-substituted trisulfide-2-oxides are prepared by treatment of 1,8-naphthalene dithiols with thionyl chloride and pyridine. The 1,2,3-trithiane-2-oxide ring adopts a sofa conformation in the solid state, with a pseudoaxial oxygen and evidence of ring strain (peri-interaction). Heating the trisulfide-2-oxides in the presence of a diene results in formal sulfur monoxide (SO) transfer to form unsaturated cyclic sulfoxides, along with a recyclable 1,8-naphthalene disulfide. The presence of o-methoxy or o-tert-butyl substituents on the naphthalene ring lowers the temperature and increases the rate at which SO transfer occurs. Trapping experiments and kinetic studies are consistent with the generation of triplet SO, followed by in situ trapping by diene. Transfer of SO also occurs upon irradiation at room temperature, but yields of sulfoxide are lower. Dehydration of the sulfoxides under Pummerer conditions gives thiophenes, including the naturally occurring thioperillene. Two dienes form thiophenes directly under the SO transfer conditions. The methodology is applied in a formal synthesis of the antiplatelet medication Plavix. [ABSTRACT FROM AUTHOR]

Two organic-inorganic hybrid compounds [Zn2(µ-4-OBz)4(py)2] · 0.5CH3OH (1) and [Zn(2-Cl-OBz)2(py)2] (2) (OBz = benzoate; 2-Cl-OBz = 2-chlorobenzoate; py = pyridine) have been synthesized from aqueous methanol at room temperature and characterized by analytical, spectroscopic, and single-crystal X-ray diffraction. Compound 1 crystallizes in space group P21/c and exhibits a dinuclear paddle-wheel-like structure with Zn-Zn separation of 2.9602(7) Å. Zn-O distances in 1 range from 2.0272(18) to 2.057(2) Å and Zn-N distances are 2.043(5) and 2.004(9) Å. Each Zn has a square-pyramidal geometry bridged by four carboxylates in the basal plane with the pyridine at the apex. The dinuclear unit also contains 0.5 methanol. Compound 2 crystallizes in space group P1 and consists of discrete molecules having a distorted tetrahedral environment around zinc; 2-chlorobenzoate and pyridine are monodentate. The observed Zn-O distances in 2 are 2.0255(19) and 2.0377(18) Å and Zn-N distances are 1.9535(14) and 1.9587(16) Å. Weak C-H-O and π-π stacking interactions between 2-chlorobenzoate and pyridine are operative in the crystal lattice of 2. Complex 2 on excitation at 340 nm exhibits luminescence at room temperature arising probably due to intraligand π-π* transition. [ABSTRACT FROM AUTHOR]

Abstract: A library of 1,4-benzodiazepines has been synthesized and evaluated against Trypanosoma brucei, a causative parasite of Human African trypanosomiasis. Benzodiazepines possessing a P2- transporter motif were found to have MIC values as low as 0.78μM. [Copyright &y& Elsevier]

A series of aryiboronates has befell synlhesizeil from the reaction of 2-{2-, (3-, or (4-(bramomethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-diaxabarolane 1 {1-3} respectively with a range of N-, S-, and O-nucleophiles, using microwave-medialed chemistry. For the synthesis of N- and S-substituted boronates, a supported base, PS-NMM, was With O-nucleophiles, a mixture of tetrabutylammonium bromide, potassium carbonate, and sodium hydroxide was employed. The resulting aminomethyl, mercaptomethyl, or alkoxy-phenoxymethyl-arylboronates were subjected lo microwave-mediated Suzuki Miyanra cuuphng reactions to afford a range of biaryls in moderate to good yields. The X-ray structures of five boronates were determined. [ABSTRACT FROM AUTHOR]

The article compares the solid-state structures of a series of seven substituted 3-methylidene-1H-indol-2(3H)-one derivatives that were determined through a single-crystal X-ray diffraction process. Six of the structures show intermolecular hydrogen bonding between the 1H-indol-2(3H)-one units. The seven derivatives are associated with the multiple-receptor tyrosine kinase inhibitor sunitinib.

Abstract: Treatment of (ArF′)2Zn(OEt2)2 (ArF′=4-C6F5C6F4) with 2equiv. of benzonitrile, 4-(phenyl)benzonitrile, 4-(pyrrolyl)benzonitrile, pyridine, 4-(phenyl)pyridine or 4-(pyrrolyl)pyridine in dichloromethane afforded the corresponding adducts (ArF′)2ZnL2 in near quantitative yield. The 2,2′-bipyridine adduct was prepared similarly. Multinuclear NMR spectroscopy indicated that zinc′s four-coordinate character was maintained in solution. The pyridine complex crystallized from dichloromethane with a solid-state structure free of face-to-face aryl–aryl interactions. In contrast, the 4-(pyrrolyl)pyridine adduct crystallized from both dichloromethane and 1,2-difluorobenzene, with solvent of crystallization, but otherwise essentially identical supramolecular architectures assembled through aryl–aryl synthons, including a face-to-face pentafluorophenyl–pyrrole interaction. [Copyright &y& Elsevier]

The reaction of the five-membered C,N-palladacycle [(L)PdCl]2, where LH= 1-methyl-5-phenyl- 1H-1,4-benzodiazepin-2(3H)-one, with 1,2-ethanebis(diphenylphosphine), dppe, leads to the formation of the bridged palladacycle. [Pd2L2(μ-dppe)Cl2] 3, which was characterised in solution by 1H and 31P NMR spectroscopy and in the solid state by X-ray crystallography. Complex 3 was tested in vitro against a number of cell lines. For example, it inhibited K562 leukaemia cells with an IC50value of 4.3 μM (1 h exposure) and displayed cathepsin B inhibitory action with an IC50 value of 3 μM. [ABSTRACT FROM AUTHOR]

Two novel enantiopure bis(pyrrolo[3,4-d])tetrathiafulvalene derivatives, substrates for preparing chiral conducting materials, show chiral crystal packing arrangements in which successive layers are rotated in accordance with an exact or approximate 43axis. The corresponding donors containing fused dihydropyrrole groups, and thus four more hydrogen atoms, form stacks along a crystal axis. [ABSTRACT FROM AUTHOR]

Abstract: 1,1′-Ferrocene biscarboxaldehyde (1) has been prepared and the aldehyde groups were subsequently protected with acetal groups to produce 1,1′-bisacetalferrocene (2). A ring-locked ferrocene was synthesised by further derivatisation of the cyclopentadiene rings at the 2,2′ positions with phosphine substituents to produce 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene (3), which was subsequently coordinated to either a nickel chloride (5) or nickel bromide (6) metal centre. The ring-locked ferrocene complexes produced 2,5′-bis-(acetal)-1,1′-diphenylphosphinoferrocene substitution patterns. The acetal protecting groups of 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene were removed to produce 1,1′-bis-carboxaldehyde-2,2′-diphenylphosphinoferrocene (4). The Cp rings of 1,1′-bisacetalferrocene were also further derivatised at the 2,2′ positions with a silane to produce the ring-locked 1,1′-siloxane-2,5′-bisacetalferrocenophane (7). The acetal protecting groups were removed from this to produce 1,1′-siloxane-2,5′-ferrocenophanecarboxaldehyde (8). For both the phosphine and siloxane electrophiles, the substitution on the Cp rings gives chiral products (obtained as racemic mixtures). Due to the highly regioselective nature of the reaction and diastereoselectivity in the products only C 2-symmetric compounds were observed without the presence of meso diastereoisomers. Subsequent ring-locking forced the Cp rings to rotate, leading to 1,1′-ring-locked ferrocenes with 2,5′-arrangement of the acetal groups (i.e. on opposite faces of the ferrocene unit). [Copyright &y& Elsevier]

The reaction of the five-membered C,N-palladacycle [(L)PdCl]2, where LH = 1-methyl-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one, with 1,2-ethanebis(diphenylphosphine), dppe, leads to the formation of the bridged palladacycle. [Pd2L2(μ-dppe)Cl2] 3, which was characterised in solution by 1H and 31P NMR spectroscopy and in the solid state by X-ray crystallography. Complex 3was tested in vitroagainst a number of cell lines. For example, it inhibited K562 leukaemia cells with an IC50value of 4.3 μM (1 h exposure) and displayed cathepsin B inhibitory action with an IC50value of 3 μM. [ABSTRACT FROM AUTHOR]

The Grignard reagent ArF'MgBr (ArF' = 4-(C6F5)C6F4) reacts withMe2SiCl,Me2SiCl2 andMe3SnCl to give the 4-nonafluorobiphenyl group 14 complexes ArF'Me3Si, (ArF')2Me2Si and ArF'Me3Sn respectively. ArF'Me3Sn undergoes only methyl group exchange when treated with BBr3, yielding ArF'Me2SnBr. The solid state structures of ArF'Me3Sn and ArF'Me2SnBr have been determined and exhibit the expected distorted tetrahedral geometries at tin. The reaction between three equivalents of ArF'MgBr and BF3 was not selective, while one equivalent of ArF'MgBr and (ArF)2BF (ArF = C6F5) reacted cleanly to give (ArF)2ArF'B. Treatment of BCl3 with three equivalents of ArF'Li, prepared at low temperature from the reaction between ArF'Br and n-BuLi, yielded (ArF')3B. The molecular structures of the acetonitrile adducts of (ArF)2ArF'B and (ArF')3B closely resemble that of (ArF)3B.NCMe. During the course of the boron investigations, reaction with adventitious water led to the structural characterization of (ArF')2BOH.OH2 as a hydrogen-bonded dimer. The Grignard reagent reacts selectively with ZnCl2 in diethyl ether giving first [(ArF')Zn(m-Cl)(OEt2)]2 then (ArF')2Zn(OEt2)2, both of which have been characterised by X-ray diffraction. The corresponding reaction with HgCl2 requires the use of tetrahydrofuran as the solvent and yields (ArF')2Hg(THF)2. [ABSTRACT FROM AUTHOR]