Catalytic Borylation of SCF3‐Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective C?H Activation at the ortho‐Position

An unprecedented reaction pathway for the borylation of SCF₃‐containing arenes using [Rh(Bpin)(PEt₃)₃] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C H activations occur with a unique regioselectivity for the position ortho to the SCF₃ group, which apparently serves as directing group. Borylated SCF₃ compounds can serve as versatile building blocks.     

Catalytic Borylation of SCF3‐Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective CH Activation at the ortho‐Position

An unprecedented reaction pathway for the borylation of SCF₃‐containing arenes using [Rh(Bpin)(PEt₃)₃] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C? H activations occur with a unique regioselectivity for the position ortho to the SCF₃ group, which apparently serves as directing group. Borylated SCF₃ compounds can serve as versatile building blocks.     

Synthesis of Anabaseine and Anabasine Derivatives: Structural Modifications of Possible Nicotinic Agonists

Coupling nicotinoyl chloride with 3,4‐dimetoxyphenethylamine under Bischler‐Napieralski cyclization afforded the isoquinoline (4) in good yield. This latter was used as starting material to obtain with only hydrobromic acid a product with demethylation at the position 7 (5). In addition, treatment of (4) with NaBH₄/MeOH gave 6,7‐dimetoxy‐1‐(pyridin‐3‐yl)‐1,2,3,4‐tetrahydroisoquinoline (6) and unexpectedly, under mild reduction of the pyridine moiety with H₂/PtO₂/AcOH/, gave 6,7‐dimetoxy‐1‐(piperidin‐3‐yl)‐1,2,3,4‐tetrahydroisoquinoline (7) as the title compound. The unusual chemical reactivity of 4 onto acidic conditions and catalytic hydrogenation allowed us to obtain anabaseine and anabasine derivatives under mild conditions.     

Microwave‐Assisted One‐Pot Synthesis of 2‐(Substituted phenyl)‐1H‐benzimidazole Derivatives

A series of 2‐(substituted phenyl)‐1H‐benzimidazole derivatives with various 5‐and 6‐position substituents (‐H, ‐CH₃, ‐CF₃) were synthesized via microwave irradiation using a short synthetic route and Na₂S₂O₅ as oxidant. This simple, fast, and efficient preparation of benzimidazole derivatives has been developed using readily available and inexpensive reagents (aldehydes and 1,2‐phenylenediamines) under solvent‐free conditions.     

Origins of regioselectivity in radical arylation of aniline: A computational study

The radical arylation of the para‐substituted anilines under three different conditions (A: arylhydrazines as the radical precursors and MnO₂ as the oxidant in acetonitrile; B: arylhydrazine hydrochlorides as the radical precursors and O₂ as the oxidant in aqueous sodium hydroxide solution; C: arenediazonium salts as the radical precursors and TiCl₃ as the reductant in aqueous hydrochloric acid solution) has been theoretically studied and the origins of the ortho/meta regioselectivity have been explored. The arylation process is suggested to contain three steps: radical generation, radical addition, and rearomatization. Calculations show that the arylation of the neutral anilines is kinetically controlled under conditions A and B, and the regioselectivity is determined by the radical addition. As a directing group, ? NH₂ plays an important role in these cases with the assistance of Mn(OH)₂ (the reduced product of MnO₂ under condition A) and Na⁺ (condition B). As for the arylation of the protonated anilines under condition C, the regioselectivity is affected by the substituents in the para‐position of anilines. Electron‐donating groups support meta‐addition and the selectivity is decided by the radical addition. Conversely, electron‐withdrawing groups favor ortho‐addition, and in this situation the arylation process is thermodynamically controlled and the regioselectivity is determined by the radical addition and rearomatization. © 2015 Wiley Periodicals, Inc.     

A new whitlockite,Ca8.42Na1.16V(PO4)7

Single crystals of a new complex phosphate, calcium sodium vanadium phosphate, Ca_8.42Na_1.16V(PO₄)₇, have been grown from a melt under an inert atmosphere. The crystal structure has rhombohedral (R3c) symmetry and belongs to the whitlockite structure type. Vanadium(III) ions occupy nearly regular octa­hedral sites (M5 with 3 point symmetry), which share corners with six PO₄ tetra­hedra to form isolated units. The calcium ions occupy eight‐ and nine‐coordinated sites. The sodium ions partially occupy one octa­hedral position and share one nine‐coordinated position with a Ca atom.     

Regioselective bromination of activated aromatic substrates with a ZrBr4/diazene mixture

A regioselective method for the bromination of phenols, ethers and anilines using a ZrBr₄/diazene mixture is described. The reaction takes place under mild reaction conditions and the bromine atom adds first at the para unsubstituted position with respect to the OH, OR or NR₂ group of the activated aromatic substrate. Less reactive compounds such as toluene, phenyl acetate, benzonitrile and trifluoromethylbenzene remain intact under the same conditions.     

A novel synthetic approach to fluorine-containing acetylenic compounds based on Nicholas reaction

The fluorine-containing dicobalthexacarbonyl complex, prepared readily from γ-fluoroalkylated propargyl acetates and Co₂(CO)₈, reacted smoothly with various nucleophiles at the propargylic position, followed by oxidative decomplexation under the influence of Fe(NO₃)₃, to afford fluoroalkylated alkynes bearing various types of alkyl side chains in good to high yields.     

Synthesis of EPA- and DHA-Enriched Structured Acylglycerols at the sn-2 Position Starting from Commercial Salmon Oil by Enzymatic Lipase Catalysis under Supercritical Conditions

There is consistent evidence that long-chain polyunsaturated fatty acids (LCPUFA) belonging to the n-3 series, i.e., eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) acids, decrease the risk of heart, circulatory and inflammatory diseases. Furthermore, the bioavailability of such fatty acids has been shown to depend on their location in triacylglycerol (TG) molecules at the sn-2 position. Consequently, great attention has been accorded to the synthesis of structured acylglycerols (sAG), which include EPA or DHA at the sn-2 position. The aim of this work was to synthesize sAG starting from deodorized refined commercial salmon oil. For this, immobilized lipase B from Candida antarctica (nonspecific) was used as a catalyst for the intra–interesterification process under CO₂ supercritical conditions (CO₂SC). According to the CO₂SC reaction time, three different fractions including sAG compounds were obtained. The location of EPA and DHA at the sn-2 position in the resulting glycerol backbone was identified by mass spectrometry (MALDI-TOF) analysis. In all fractions obtained, a marked decrease in the starting TG content was observed, while an increase in the DHA content at the sn-2 position was detected. The fraction obtained after the longest reaction time period (2 h) led to the highest yield of sn-2 position DHA in the resulting sAG molecule.     

Stepwise synthesis of two inorganic–organic hybrids based on the manganese monosubstituted Keggin polyanion chains

Two new hybrid compounds based on the manganese monosubstituted Keggin polyanion chains, [H₂bpy][Ag(bpy)]₂[HPMnMo₁₁O₃₉] (1) and [H₂bpy]₂[Hbpy][PMnMo₁₁O₃₉]·H₂O (2), (bpy = 4,4′-bipyridine) have been stepwise synthesized under hydrothermal condition and characterized by elemental analyses, IR spectra, thermogravimetry, and single-crystal X-ray diffraction technique. Structural characterization reveals that although both 1 and 2 contain manganese monosubstituted Keggin polyanion chains, the polyanion chains are not in the full consistent way. In 1, the neighboring manganese monosubstituted Keggin clusters are connected via sharing the para position oxygen atoms of the clusters to form a linear polyanion chain in which the monosubstituted Keggin clusters are further grafted by silver coordination polymer chains forming a 2D network. Whereas the polyanion chain in 2 exhibits a zigzag structure, which is formed by sharing the metaposition terminal oxygen atoms of the clusters, rather than para position terminal oxygen atoms as that in 1. Each zigzag chain contacts with four adjacent chains along four directions through short interspecies contacts, forming a 3D supramolecular framework. The protonated Hbipy⁺ and H₂bipy²⁺ molecules as the counter cations exist in voids of the supramolecular framework in 2. Furthermore, photocatalytic experiments indicate that 1 has good activities for photocatalytic degradation of RhB under UV irradiation.     

Regioselective Oxidation Approaches to Concise Synthesis of (±)‐Canabisin D

The regioselective effects of tert‐butyl or bromine as the position‐protecting group of feruloytyamide on the oxidative coupling reactions for the synthesis of natural (±)‐canabisin D were investigated in detail. The coupling yield of 8‐8‐coupled aryldihydronaphthalene product of 5‐Br‐feruloytyamide was higher than that of tert‐butyl substituted precursor under FeCl₃·6H₂O‐acetone‐water oxidative condition.     

Electrophilic substitution in eleven-vertex metallacarborane 1,2,4-CpCoC2B8H10

Bromination and mercuration of cobaltacarborane 1,2,4-CpCoC₂B₈H₁₀ were investigated. Mercuration under mild conditions (Hg(OCOCF₃)₂ in CH₂Cl₂) afforded the only monomercurated complex containing the mercury atom at position 6. Bromination gave rise to 3-mono-, 6-mono-, or 6,9-disubstituted derivatives depending on the reaction conditions. The mercurated derivative was studied by the X-ray diffraction method.     

Selective hydroxylation of adamantane and its derivatives

A general method was developed for hydroxylation into the nodal position of adamantane and its 1- and 2-substituted derivatives employing systems H₂O-CBr₄ (BrCCl₃, CCl₄) in the presence of complexes of Pd, Ni, Ru, Co, Mo, W, and Fe. The oxidants in the systems are hypochlorous (HOCl) or hypobromous (HOBr) acids generated from water and halomethanes under the reaction conditions.     

Change of Boron Substitution Improves the Lasing Performance of Bodipy Dyes: A Mechanistic Rationalisation

Bodipy laser dyes are highly efficient but degrade rapidly in solution by reacting with in situ generated singlet oxygen (¹O₂). To increase the lasing lifetimes of these dyes, we have designed and synthesised two different congeners of the widely studied Pyrromethene 567 (PM567) by substitution at the boron centre and/or at both the boron centre and the meso position. The two new dyes showed high lasing efficiencies with increased photostability. The results of theoretical and pulse radiolysis studies revealed that the substitution at the boron centre reduced the ¹O₂ generation capacity of these dyes as well as their rate of reaction with ¹O₂, thereby enhancing their lifetimes even under lasing conditions.     

The study of copper dissolution in aqueous and nonaqueous systems DMSO-HX<Subscript>solv</Subscript> (solv = H<Subscript>2</Subscript>O,X = Br,Cl; solv = MeCN,PhNO<Subscript>2</Subscript>; X = Cl) by resistometric method

Copper dissolution in the aqueous systems DMSO-HX_solv (solv = H₂O; X = Cl, Br) under the inert atmosphere and under aerobic conditions at different acid concentrations was studied by the resistometric method by measuring the resistance of a metal sample in the course of the reaction. The overall activity of the system decreases with a decrease in the concentration of the starting hydrohalic acid. The rate of copper dissolution in the extremum points also decreases. The process of the metallic copper dissolution in nonaqueous systems, such as DMSO-HCl_solv (solv = MeCN, PhNO₂), was studied. In the latter systems, as opposed to aqueous systems, only one maximum in the plot of the copper dissolution rate versus the component ratio is observed. The change in the nature of the solvent in the donor-acceptor electron transport system DMSO-HCl_solv (solv = H₂O, MeCN, PhNO₂) results in the change in the position of the maximum of the copper dissolution rate, as well as in the change in its value. The rate of copper dissolution in the above mentioned systems varies in the following series: H₂O < MeCN < PhNO₂.     

A new increasing delocalization of M=3d-elements (Ti, Fe, Co) in the channels network of the ternary MyMo6Se8 Chevrel phases

A structural investigation on single crystals of M_yMo₆Se₈ Chevrel phases (M=3d: Ti, Fe, and Co) has been carried out. These latter compounds as well as others with Cr, Mn, and Ni atoms make part of a new original family of Chevrel phases. The M ions occupy new interstices in the tridimensional channels network never observed in the other classical Chevrel phases as Li_y, Cu_y Mo₆X₈. They occupy only cavity 2 centered on and with a progressive delocalization of the M cation versus the nature of the cation from the center of the cavity to the outside . The position in cavity 2 is different from the position of the Cu (2) atoms, the second position of the copper atoms in the channels of the Cu_yMo₆X₈ compounds. This new position reinforces the interaction with the Mo₆ cluster, and may be able to involve new remarkable physical properties as thermoelectric properties.     

Recyclable silica-supported iodoarene-RuCl3 bifunctional catalysts for oxidation of alcohols and alkylarenes

Novel, efficient, and recyclable bifunctional catalysts bearing SiO₂-supported RuCl₃ and iodoarene moieties were developed and used for environmentally benign oxidation of alcohols or alkylarenes at the benzylic position. These reactions in the presence of oxone as stoichiometric oxidant afforded the corresponding carbonyl compounds in high yields under mild conditions and convenient work-up. Furthermore, these SiO₂-supported bifunctional catalysts can be recovered by simple filtration and directly reused.     

Sulfobridged Polynuclear Complexes of Platinum(II) and Palladium(II)

When the platinum(II) and palladium(II) salts interact with ligands such as cystamine-(mercamine) HSCH₂CH₂NH₂ and 2-mercaptoethanol HSCH₂CH₂OH under certain conditions, polynuclear complexes of the compositions are obtained: [Pt₆(SCH₂CH₂NH₂)₈]Cl₄. 5H₂O and [Pd₆(SCH₂CH₂OH)₈]Cl₄. In a comparative study of the IR and X-ray spectra of synthesized complexes and ligands, as well as the results of X-ray diffraction studies, it was established that sulfur atoms of 2-mercaptoethanol occupy a bridge position with a mixed coordination of ligands in the palladium complex. In the platinum(II) complex bidentate coordination of ligands is realized through sulfur and nitrogen atoms.     

A fluoroaryl substituent with spectator function: Reactivity and structures of cyclic and acyclic HF4C6-substituted phosphanes

The reactivity of a series of phosphanes with a fluoroaryl group (HF₄C₆-) carrying a spectator function in para position has been explored with respect to the formation of low coordinated and phosphorus rich phosphanes. An asymmetric diphosphene has been indentified as an intermediate in the synthesis of a linear 1,3-dihydrophosphane, while the symmetric diphosphene undergoes 2 + 2 cycloaddition under formation of the corresponding cyclotetraphosphetane for which a crystal structure could be obtained. Attempts to synthesize HF₄C₆-substituted iminophosphanes generally failed, which is attributed to the electronic nature of the corresponding precursors as suggested by quantum chemical calculations.     

2-Naphthol Moiety of Neocarzinostatin Chromophore as a Novel Protein-Photodegrading Agent and Its Application as a H2O2-Activatable Photosensitizer

A 2-naphthol derivative 2 corresponding to the aromatic ring moiety of neocarzinostatin chromophore was found to degrade proteins under photo-irradiation with long-wavelength UV light without any additives under neutral conditions. Structure–activity relationship studies of the derivative revealed that methylation of the hydroxyl group at the C2 position of 2 significantly suppressed its photodegradation ability. Furthermore, a purpose-designed synthetic tumor-related biomarker, a H₂O₂-activatable photosensitizer 8 possessing a H₂O₂-responsive arylboronic ester moiety conjugated to the hydroxyl group at the C2 position of 2 , showed significantly lower photodegradation ability compared to 2 . However, release of the 2 from 8 by reaction with H₂O₂ regenerated the photodegradation ability. Compound 8 exhibited selective photo-cytotoxicity against high H₂O₂-expressing cancer cells upon irradiation with long-wavelength UV light.