Thiophene-based macrocycles via the Suzuki–Miyaura cross coupling reaction

Suzuki–Miyaura cross coupling reaction was used for access to new macrocycles exhibiting oligoethyleneoxide bridges and embedding bithiophene, terthiophene or 3,7-bis(thiophen-2-yl)-N-ethyl-10H-phenothiazine units. The synthesis was performed under various reaction conditions and different coupling types in order to establish the correlation between yields and employed solvents and bases. The structure of the compounds was supported by single crystal X-ray diffractometry, NMR, and MS experiments.     

Dichloroimidazolidinedione-activated one-pot Suzuki–Miyaura cross-coupling of phenols

The first general method for the Suzuki-type cross-coupling of phenols with aryl boronic acids using dichloroimidazolidinedione (DCID) as a new reagent is presented. In the presence of DCID and Pd/metal–organic framework (MOF), coupling of aryl boronic acids with a wide range of phenols, was carried out smoothly in tetrahydrofuran (THF) at reflux conditions to afford the cross-coupling products in good to excellent yields. The structures of all compounds were corroborated by ¹H- and ¹³C-NMR. A plausible mechanism for this type of reaction is proposed.     

Palladium-catalysed Suzuki–Miyaura coupling reactions of Bromhexine and Ambroxol

The Suzuki–Miyaura coupling reaction was applied for the synthesis of biologically relevant derivatives of known mucolytic agents Bromhexine and Ambroxol. Using commercially available electron-rich and electron-poor arylboronic acids the desired products are obtained in moderate to high yields (42–81%).     

Synthesis of asymmetric 3,5-diaryl-4H-1,2,6-thiadiazin-4-ones via Suzuki–Miyaura and Stille coupling reactions

Asymmetric 3,5-diaryl substituted 4H-1,2,6-thiadiazin-4-ones can be prepared from 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (1) via a multi-step protocol: selective nucleophilic mono-chloro substitution gives either the mono-methoxy or benzyloxy substituted mono-chlorothiadiazinones that can be phenylated via Suzuki–Miyaura coupling. Subsequent BBr₃ mediated dealkylation gives 3-hydroxy-5-phenyl-4H-1,2,6-thiadiazin-4-one (9) that can be activated by a modified Finkelstein halodehydroxylation via the triflate, enabling further arylation reactions using Suzuki–Miyaura or Stille coupling chemistry.     

Calculated linear free energy relationships in the course of the Suzuki–Miyaura coupling reaction

Concerning the Suzuki–Miyaura coupling reaction, we report detailed theoretical study of thermodynamic data (at the B3PW91/LANL2DZ level with polarization functions added and including dispersion force corrections) concerning each step of the catalytic cycle. In each case, we have observed a Hammett plotting of δE or δG versus σ_p of substituent of various reagents, which accounts for multiple-substituent effects. Therefore, these calculations predict the influence of the electron-donor/electron-acceptor character of each substituents on the thermodynamic requirements for reaction. Our major conclusion is that the transmetalation between a palladium hydroxo complex and an arylboronic acid is preferable to the transmetalation with a palladium bromo complex. Moreover, the alkaline hydrolysis of palladium bromo complex appears as a strong exothermic reaction. Concerning the reductive elimination step alternative processes have been investigated.     

Suzuki–Miyaura coupling of quinazolines containing an unprotected NH2 group: Synthesis and biological testing of quinazoline derivatives

A robust approach to 4-amino quinazoline bi-aryl compounds was developed through Suzuki–Miyaura coupling reaction of quinazoline containing an unprotected NH₂ group and arylboronic acids. Pd(dcpf)Cl₂ was found to be an efficient catalyst for the reaction. All the compounds were evaluated for antimicrobial activity against gram-positive and gram-negative bacteria and fungi. One of the compounds, 3l, found to be more active against Candida albicans than the standard Miconazole.     

Catalysis of the Suzuki–Miyaura coupling reaction in water by heteroannular cyclopalladated ferrocenylimine complexes

Catalytic studies on the air- and moisture-stable triphenylphosphine (PPh₃) adducts of heteroannular cyclopalladated ferrocenylimines [PdCl{C₅H₄FeC₅H₄CHRN=CHC₄H₃X}(Ph₃P)] (R = H, CH₃; X = S, O) indicate that they are all effective catalysts for the Suzuki–Miyaura coupling reaction of activated aryl bromides with phenylboronic acid in water under air atmosphere. Typically, using 1 mol‰ of catalyst in the presence of 1.2 equivalents of K₃PO₄ as base in water at 100 °C provided the corresponding biaryls in good to excellent yields. Meanwhile, the structure of [PdCl{C₅H₄FeC₅H₄CH(CH₃)N=CHC₄H₃S}(PPh₃)] has been established by the single-crystal X-ray diffraction technique. According to the crystal structure, the palladium atom is bound to the unsubstituted Cp ring, showing the four-coordinate structure typical of palladium complexes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Preparation of C-arylglycals via Suzuki–Miyaura cross-coupling of dihydropyranylphosphates

The preparation of C-arylglycals has been accomplished by employing the Suzuki–Miyaura cross-coupling reaction of dihydropyranylphosphates with arylboronate esters. The reaction is tolerant of both electron-donating (EDG) and electron-withdrawing (EWG) groups on the aromatic ring and affords the corresponding C-arylglycals in good to excellent yields (68–97%). Additionally, the ketene acetal phosphate derived from 6-deoxy-3,4-di-O-benzyl-l-rhamnal also couples efficiently to yield C-arylglycals in excellent yields.     

Palladium-catalyzed one-pot Suzuki–Miyaura cross coupling followed by oxidative lactonization: a novel and efficient route for the one-pot synthesis of benzo[c]chromene-6-ones

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Biogenous iron oxide-immobilized palladium catalyst for the solvent-free Suzuki–Miyaura coupling reaction

Iron oxide produced by iron-oxidizing bacteria, Leptothrix ochracea, (biogenous iron oxide: BIO) was used as a support for immobilized palladium catalysts with organic cross-linkers. Palladium immobilized on BIO bearing imidazolium chloride delivered the desired biaryl products in sufficient yields in the Suzuki–Miyaura coupling reactions under solvent-free conditions and could be reused several times without significant loss of catalytic activity. It is shown that BIO can be exploited as a useful support for immobilization of palladium and the BIO-immobilized palladium catalyst effectively promotes the solvent-free Suzuki–Miyaura coupling reactions.     

Synthesis and characterization of hydrophilic theophylline base compounds and their use as ligands in the microwave assisted Suzuki–Miyaura couplings of halopyridines in water

Xanthine derivatives, caffeine (L1), theobromine (L2), theophylline (L3), 7-(β-hydroxyethyltheophylline) (L4), (7-(2,3-dihydroxypropyl)theophylline) (L5), and theophylline 7-acetic acid (L6) and the acetylated derivatives of the later three (L7–L9) were employed as ligands for the in situ palladium catalyzed Suzuki–Miyaura cross couplings of a series of halogenated pyridines. Optimized conditions were found where the diacetylated ligand (L8) was determined to be the best for this process, producing good to excellent yields in the couplings of halogenated anilines with phenylboronic acid under mild reaction conditions in water using microwave irradiation.     

Efficient synthesis of diversely substituted pyrimidines by palladium catalyzed Suzuki–Miyaura coupling

An efficient synthesis of 2-aryl/heteroaryl substituted pyrimidinyl ethanones 4(a–t) was developed using a palladium-catalyzed Suzuki–Miyaura coupling reaction strategy. Use of Pd(OAc)₂ in the presence of PPh₃ and Na₂CO₃ in 1,4-dioxane solvent was found to be the most effective reaction condition.     

Effects of structure and electronic properties of D-π-A organic dyes on photovoltaic performance of dye-sensitized solar cells

Herein,we examine the performance of dye-sensitized solar cells containing five D-π-A organic dyes designed by systematic modification of π-bridge size and geometric structure.Each dye has a simple push-pull structure with a triarylamino group as an electron donor,bithiophene-4,4-dimethyl-4 H-cyclopenta 1,2-b:5,4-b’]dithiophene(M11),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophenethiophene(M12),thiophene-4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M13),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene-benzene(M14),and 4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M15)units asπ-bridges,and cyanoacrylic acid as an electron acceptor/anchor.The extension of theπ-bridge linkage favors wide-range absorption but,because of the concomitant molecular volume increase,hinders the efficient adsorption of dyes on the TiO₂ film surface.Hence,higher loadings are achieved for smaller dye molecules,resulting in(i)a shift of the TiO₂ conduction band edge to more negative values,(ii)a greater photocurrent,and(iii)suppressed charge recombination between the photoanode and the redox couple in the electrolyte.Consequently,under one-sun equivalent illumination(AM 1.5 G,100 mW/cm²),the highest photovoltage,photocurrent,and conversion efficiency(η=7.19%)are observed for M15,which has the smallest molecular volume among M series dyes.     

Immobilization of palladium nanoparticles as a recyclable heterogeneous catalyst for the Suzuki–Miyaura coupling reaction

This work describes the synthesis of Pd nanoparticles that are stabilized on CaAl-layered double hydroxide functionalized with Tris (tris(hydroxymethyl)aminomethane). The synthesized catalyst is characterized by several different analyses and has been successfully applied to the Suzuki–Miyaura reaction.     

Synthesis of immobilized nanopalladium on polymer-supported Schiff base, and study of its catalytic activity in the Suzuki–Miyaura reaction

Abstract  

Nanopalladium particles immobilized on a matrix of poly(vinyl chloride) (PVC)-supported Schiff base were prepared from PVC with sequential attachment of ethylenediamine and salicylaldehyde, followed by treatment with an ethanolic solution of palladium chloride. The as-prepared catalyst was found to be air and moisture-stable and to have significant catalytic activity in Suzuki–Miyaura reactions under mild operating conditions. Various phenyl halides were coupled with phenylboronic acid in aqueous ethanol, under air, to afford the corresponding cross-coupled products in good yields. Furthermore, the catalyst can be easily recovered by simple filtration and reused for up to five cycles without losing its activity.     

Synthesis and spectroscopic properties of ring-fused thiophene bridged push–pull dyes and their application in dye-sensitized solar cells

Bisdimethylfluorenylamino-based push–pull dyes bearing one or two benzo[c]thiophene and its precursor bicyclo[2.2.2]octadiene (BCOD) fused thiophene as π bridge have been synthesized. The effect of fused-ring on thiophene bridge for the spectroscopic and electrochemical properties of these dyes has been investigated. Dye-sensitized solar cells fabricated with these dyes show moderate photovoltaic properties.     

Preparation and characterization of PEPPSI-palladium N-heterocyclic carbene complexes using benzimidazolium salts catalyzed Suzuki–Miyaura cross coupling reaction and their antitumor and antimicrobial activities

New palladium complexes were efficiently synthesized from the reaction of benzimidazolium salts 2a–e, potassium carbonate (K₂CO₃) and palladium chloride (PdCl₂) in pyridine (for 3a–e). The catalytic activity of these complexes in a catalytic system including palladium complexes and K₂CO₃ in DMF-H₂O was evaluated in Suzuki–Miyaura cross-coupling reactions of aryl bromides and chlorides with phenylboronic acid. Our novel complexes show excellent catalytic activities with high turnover numbers (TON) and high turnover frequencies (TOF) (e.g. for the Suzuki–Miyaura reaction: TON up to 370 and TOF up to 123.3?h^?1). Both benzimidazolium salts 2a–e and complexes 3 have been characterized using spectroscopic data and elemental analysis. The antimicrobial activity of the N-heterocyclic carbene palladium complexes 3a–e varies with the nature of the ligands. Also, the IC₅₀ values of both, complexes (3a–e) and benzimidazoles 2a–e, have been determined. In addition, the new palladium complexes were screened for their antitumor activity. Complexes 3e and 3d exhibited the highest antitumor effect with IC₅₀ values 6.85?μg/mL against MCF-7 and 10.75?μg/mL against T47D, respectively.     

Synthesis and properties of organic–inorganic hybrid liquid crystal gels

Organic–inorganic hybrid liquid crystal (LC) gels have been synthesised by the thiol-ene reaction of a multifunctional cyclic siloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (TVMCTS) and alkane dithiols, 1,6-hexanedithiol (HDT) or 1,9-decanedithiol (DDT), in LC matrices, 4-cyano-4?-pentylbiphenyl (5CB) or 4′-n-octyl-4-cyano-biphenyl (8CB). The LC gels were prepared in an isotropic phase at 70°C or mesophases at 25°C using radical initiators. The phase transition temperatures from a mesophase to an isotropic phase of the resulting gels were lower than those of the original LCs. The gels containing 8CB (8CB gels) prepared at 25°C showed two phase transitions: smectic-to-nematic and nematic-to-isotropic transitions. By contrast, the 8CB gels synthesised in the isotropic phase showed only one phase transition from smectic phase directly to isotropic phase. Reaction conversions in the LC gels prepared at 70°C were higher than that in the gels prepared at 25°C. Scanning microscopic light scattering analysis of the LC gels cleared homogeneous small size mesh with a small amount of large defect. Polarisation micrographs of the LC gels showed framed optical textures derived from the LC molecules at room temperature. The LC gels containing more than 90 wt% of LC showed electro-optic response.     

Evaluating the photovoltaic properties of two conjugated polymers synthesized by Suzuki polycondensation and direct C–H activation

Two conjugated polymers HXS-1 and PDFCDTBT were prepared by direct C–H activation and Suzuki polycondensation and their chemical structures were characterized by 1H NMR spectroscopy.The molecular weight of conjugated polymer synthesized by direct C–H activation is lower than the corresponding polymers prepared by Suzuki polycondensation.Conjugated polymers synthesized by direct C–H activation have considerable solubility in common organic solvents and form amorphous film.The photovoltaic property of conjugated polymers synthesized by direct C–H activation is inferior to the corresponding polymers synthesized by Suzuki polycondensation.     

Polyarenes prepared by Suzuki–Miyaura reaction via condensation of sumanene and 3,4:9,10-perylenetetracarboxydiimide derivatives: Synthesis and chemical transformations

A sumanene-containing polyarene with side epoxy groups has been obtained for the first time by the sequential chemical transformations of initial polyarene. The latter was prepared by the condensation of diiodosumanene and diboryl derivative of perylenetetracarboxydiimide. The epoxy-containing polyarene can provide a basis for promising negative electron resist for 12-nanometer chip manufacturing technology.