Aryl Derivatives Research Articles

3,3]-Sigmatropic Shifts and Retro-ene Rearrangements in Cyanates, Isocyanates, Thiocyanates, and Isothiocyanates of the Form RX-YCN and RX-NCY

Retro-ene type [2π + 2π + 2σ] and [3,3]-sigmatropic shift reactions involving the substituent groups R in heteroatom-substituted cyanates and thiocyanates RX-YCN and the isomeric isocyanates and isothiocyanates of the type RX-NCY (X = CR(2), NR', O, or S; Y = O or S) have been investigated computationally at the B3LYP/6-311++G(d,p) level. Retro-ene reactions of alkyl derivatives of the title compounds afford alkenes, imines, carbonyl and thiocarbonyl compounds together with HNCO (HNCS) or HOCN (HSCN). [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the corresponding allyl, propargyl, benzyl, and aryl derivatives causes allylic rearrangements, propargyl-allenyl rearrangement, conversion of benzyl cyanates to o-isocyanatotoluenes, and conversion of N-cyanatoarylamines to o-isocyanatoanilines, etc. The corresponding rearrangements of allyl thiocyanates, arylamino thiocyanates and isothiocyanates, and arylsulfenyl thiocyanates and isothiocyanates are also described.

ChemInform Abstract: Synthesis, Reactions, and Biological Activity of 1,4‐Thiazepines and Their Fused Aryl and Heteroaryl Derivatives

AbstractReview: 76 refs.

Pd-catalyzed decarboxylative cross-couplings of potassium malonate monoesters with aryl halides

An efficient catalytic protocol for Pd-catalyzed decarboxylative cross-coupling of potassium malonate monoesters and derivatives with aryl bromides and chlorides are described. Because of its broad applicability, this new catalytic system provides an alternative method for the preparation of diverse aryl acetic acids and derivatives.

Spectral, electrochemical and structural study of aryl derivatives of trans-stilbenes

Aryl-substituted alkenes are promising materials for optoelectronic and photovoltaic applications. In this study we report a new series of stilbene derivatives with aromatic substituents. UV-vis absorption and fluorescence spectra of the studied compounds are presented. The optical properties are found to be dependent on dihedral angle and orbital delocalization between side substituents and the central stilbene moiety, as well as on relaxation of the excited state geometry. Especially the anthracene derivative presents different geometry and excited state properties than other studied compounds. The conclusions are supported by theoretical quantum-chemical analysis at the DFT level. Depending on the type of aromatic side substituents the HOMO orbital is localized either mainly on the central vinylene or the outmost aryl moieties. This affects the reactivity of these compounds in electrochemical reactions as well as the type of oxidation products. The thiophene derivative undergoes polymerization during oxidation and a conjugated polymer is produced while anthracene, phenylene and pentafluorophenylene derivatives undergo irreversible oxidation with creation of unconjugated products.

Synthesis and Antimalarial Activity of Substituted Pyrazole Derivatives

The development of new antimalarial drugs is an urgent priority considering the increasing prevalence of drug-resistant Plasmodium falciparum parasites. A series of pyrazoles are described as part of efforts directed toward the synthesis of some potent antimalarial agents. The replacement of the ester group as a substituent in the pyrazole ring by nitrile group caused a precipitous loss of activity as antimalarial due to the lack of hydrogen-bond formation. Further modification of the heterocyclic ring to give substituted aryl derivatives afforded potent antimalarial derivatives: methyl 5-amino-3-anisidinepyrazole-4-carboxylic acid 3a (IC50: 0.149 mumol/l) and methyl 5-amino-3-(m anisidin)pyrazole-4-carboxylic acid 3c (IC50: 0.15 mumol/l). The synthesis, structure-activity relationships (SAR), X-ray crystallography and pharmacological activity associated with these series of compounds are discussed.

Synthesis and anthelmintic activity of some hybrid Benzimidazolyl-chalcone derivatives

Purpose: To synthesize hybrid benzimidazolyl-chalcone derivatives, evaluate their anthelmintic activity, and establish some structural elements which could lead to induction and enhancement of this activity.Methods: A series of 1-(1H-benzimidazol-2-yl)-3-aryl-2-propen-1-one compounds (6a-z) was synthesized by condensation reaction of 2-acetylbenzimidazole with aryl and heteroaryl aldehyde derivatives. The physicochemical characterization of these benzimidazolyl-chalcones was carried out by nuclear magnetic resonance spectroscopy (1H and 13C NMR) and mass spectroscopy (MS). All compounds were screened in vitro for their nematicidal activity against Haemonchus contortus in larval development assay. The anthelmintic activities obtained were compared with those of anthelmintic reference drugs (fenbendazole and ivermectin); 1,3-diphenyl-2-propen-1-one also used as reference for chalcone.Results: Compounds 6a, 6g, 6w and 6y showed good nematicidal activity (LC100) at 0.002 and 0.0092 μg/ml. The activity of these four benzimidazolyl-chalcones is nearly equal to that of fenbendazole. It is also interesting to know that these compounds have anti-haemonchus activity which is equal or more efficient than ivermectin. Four other compounds (6d, 6h, 6o and 6t) possess interesting anthelmintic activities at 0.68 and 0.16 μg/ml.Conclusion: Preliminary structure-activity relationship studies revealed that arylpropenone group in position 2 of the benzimidazole ring can be considered as new pharmacophore for nematicidal activity.Keywords: Benzimidazole, Chalcone, Anthelmintic activity, Haemonchus contortus

A novel fused 1,2,4-triazine aryl derivative as antioxidant and nonselective antagonist of adenosine A2A receptors in ethanol-activated liver stellate cells

It has been detected that hepatic adenosine A2A receptors play an active role in the pathogenesis of hepatic fibrosis and suggest a novel therapeutic target in the treatment and prevention of hepatic cirrhosis. In this paper we examined if our new triazine derivative (IMT) can inhibit ethanol-induced activation of HSCs measured as increased α-SMA, collagen synthesis and enhanced oxidative stress in rat liver stellate cells. We also investigated its influence on cytokines (TGF-β, TNF-α) synthesis, MMP-2 and TIMP-1 production and ethanol-induced intracellular signal transduction. Moreover, with using of known adenosine A2A receptor agonist (CGS 21680), and antagonist (SCH 58261) we examined if this triazine derivative acts on adenosine receptors.We detected a strong antagonistic action of new triazine derivative (IMT) on ethanol-induced rat liver stellate cells activation, observed as a significant decrease in α-SMA, collagen synthesis, reactive oxygen species production, TGF-β, TNF-α, MMP-2 and TIMP-1 production as well as JNK, p38MAPK, NFκB, IκB, Smad3 phosphorylation. Moreover, IMT strongly inhibited activation of stellate cells by known selective agonist of adenosine A2A receptor (CGS 21680). When known A2A receptor antagonist (SCH 58261) was used together with IMT this effect was not spectacular. Additionally, only slight enhancement of inhibition was observed when cells were pretreated both IMT with SCH 58261, hence we suppose that IMT acts as nonselective antagonist of A2A receptors, and, besides its antioxidant activity, also by this way inhibited ethanol-induced stellate cell activation.

Aryl and Acyclic Unsaturated Derivatives of Thioguanine and 6- Mercaptopurine: Synthesis and Cytotoxic Activity

Aryl and Acyclic Unsaturated Derivatives of Thioguanine and 6- Mercaptopurine: Synthesis and Cytotoxic Activity

2-methoxy-5-bromophenyl antimony compounds. Synthesis and structure

Reaction of 2-methoxy-5-bromophenyllithium with antimony trichloride in diethyl ether affords tris-(2-methoxy-5-bromophenyl)antimony benzene solvate I. Its structure and chemical transformations into the new antimony aryl derivatives were studied.

Bay Region Borylation of Perylene Bisimides

AbstractNovel bispinacolborane‐N,N′‐bis(octyl)‐3,4,9,10‐perylenetetracarboxylic acid bisimide (PBI) was synthesized in high yield. The title compound is a key intermediate in the preparation of PBI aryl derivatives through Suzuki cross‐coupling by using a large variety of easily accessible aryl halides. The benign effect of a nonpolar solvent, mild base, and high reaction temperature on the borylation reaction was studied, and the reaction conditions were optimized accordingly. To demonstrate the potential and flexibility of the proposed building block, two corresponding bisarylperylene bisimides were prepared in high yields.

Aryl nitroporphycenes and derivatives: first regioselective synthesis of dinitroporphycenes

The nitration reaction of 2,7,12,17-tetraphenylporphycene has been studied. The use of AgNO3 and a mixture of acetic acid and 1,2-dichloroethane as a mild nitrating system provides an optimized preparation of 9-nitro-2,7,12,17-tetraphenylporphycene and a regioselective synthesis of 9,20-dinitro-2,7,12,17-tetraphenylporphycene. While 25 min of reaction are needed to obtain the mononitrated compound, 4 h are necessary to yield a mixture of 9,20-dinitro and 9,19-dinitro 2,7,12,17- tetraphenylporphycene in a proportion of 3 to 1. From this mixture, the geometric isomers can be isolated by fractional crystallization. 9-Nitro-2,7,12,17-tetraphenylporphycene can be reduced to the corresponding amino derivative, which is the starting material to obtain 9-(glutaric methylesteramide)- 2,7,12,17-tetraphenylporphycene, a versatile derivative useful for conjugation.

Synthesis, reactions, and biological activity of 1,4-thiazepines and their fused aryl and heteroaryl derivatives: a review

This review article is an attempt to survey the literature describing synthetic methods, reactions, and applications of the seven-membered 1,4-thiazepine system and its related derivatives.

ChemInform Abstract: Copper‐Catalyzed Trifluoromethylation of Aryl and Vinyl Boronic Acids with an Electrophilic Trifluoromethylating Reagent.

AbstractTogni′s reagent (I) under mild conditions is highly suitable for the synthesis of various (het)aryl derivatives, which are especially of pharmaceutical interest.

Deprotonative Metalation of Aromatic Compounds by Using an Amino‐Based Lithium Cuprate

Deprotonative cupration of aromatic compounds by using amino-based lithium cuprates was optimized with 2,4-dimethoxypyrimidine and 2-methoxypyridine as the substrates and benzoyl chloride as the electrophile. [(tmp)(2)CuLi] (+2 LiCl) (tmp=2,2,6,6-tetramethylpiperidino) was identified as the best reagent and its use was extended to anisole, 1,4-dimethoxybenzene, other substituted pyridines, furan, thiophene and derivatives, and N-Boc-indole (Boc=tert-butyloxycarbonyl). Of the electrophiles employed to attempt the interception of the generated aryl cuprates, aroyl chlorides, iodomethane, and diphenyl disulfide efficiently reacted. In addition, different oxidative agents were identified to afford symmetrical biaryls. Finally, palladium-catalyzed coupling with aryl halides was optimized and allowed the synthesis of different aryl derivatives in medium to good yields.

Twisted molecular geometry and localized electronic structure of the triplet excited gem-diphenyltrimethylenemethane biradical: substituent effects on thermoluminescence and related theoretical calculations

Substituent effects on the energies of electronic transitions (ETs) between the triplet excited and ground states of gem-diphenyltrimethylenemethane biradicals ( 3 2a ) were explored by using thermoluminescence (TL) spectroscopy and density functional theory (DFT) including time-dependent (TD) DFT. Linear free energy (Hammett) analyses of TL energies of a variety of para-substituted aryl derivatives of 3 2 * gave reasonable correlations with the substituent constant, σ . The slope of Hammett plots of the data are nearly identical to one obtained from a similar analysis of the photoluminescence (PL) energies of the structurally-related 1,1-diarylethyl radicals ( 3 *). The results suggest that TL of 3 2 * and PL of 3 * derive from a common diarylmethyl radical fluorophore. This interpretation is also supported by the DFT and TDDFT calculated electronic structures and ET energies of 3 2 and 3 . Thermodynamic and kinetic analyses of the charge recombination (CR) process between 2 + and 1 −, which generates 3 2 *, revealed that substituents not only alter the TL energies but also the TL intensities of 3 2 *. The observations made in this effort demonstrate that 3 2 * as well as 3 2 and 2 + have greatly twisted molecular geometries and highly localized electronic structures.

Synthesis of Conjugated Tri(hetero)aryl Derivatives Based on One-Pot Double Suzuki-Miyaura Couplings Using Bifunctional Dipotassium Phenylene-1,4-Bis(Trifluoroborate)

An efficient one-pot double Suzuki-Miyaura cross-­coupling reaction between bifunctional phenylene-1,4-bis(potassium trifluoroborate) and aryl and heteroaryl bromides is described. The scope and limitations of this methodology that enables the synthesis of tri(hetero)aryl derivatives, potentially useful as drugs and in the field of materials science, have also been probed.

Pd-Catalysed Direct 5-Arylation of 1-Methylpyrazole with Aryl Bromides

1-Methylpyrazole was found to be a suitable partner for palladium-catalyseddirect arylation through C-H activation/functionalisationusing aryl bromides. The reaction conditions and the nature of thecatalyst were found to have a determining influence on the selectivity.The use of an excess of pyrazole (4 equiv), and only 0.5-1mol% palladium(II) acetate as the catalyst, potassium acetate asthe base and DMAc as the solvent, promotes the 5-arylation in moderateto high selectivities and yields. A wide variety of aryl and heteroarylbromide derivatives have been successfully employed. Their electronicand steric properties also have an influence on the regioselectivitiesand yields of the coupling products. Both electron-poor and electron-richaryl bromides gave satisfactory results, although, very congestedproducts were obtained with lower regio-selectivities.

Synthesis and Crystal Structure of 13-<i>cis</i>-Retinoate Aryl Derivatives

A series of 13-cis-retinoate aryl derivatives were synthesized from 13-cis-retinoic acid and phenols or arylalcohol with dicyclohexylcarbodiimide (DCC) as reagent and 4-dimethylaminopyridine (DMAP) as catalyst. Their structures were characterized by1H,13C NMR, IR and MS. The crystal of 3a has been determined by single crystal X-ray diffraction analysis and its molecular structure has been confirmed. Compound 3a belongs to monoclinic system with space group P2 (1)/c, a = 22.235 (3) Å, b = 7.4117 (10) Å, c = 15.990 (2) Å, β = 109.253 (3) °, V = 2487.7 (6) Å3, Z = 4, R = 0.0613, ωR = 0.01437.

Reaction of 2-amino-5,5-bis(hydroxymethyl)-1-methyl-1,5-dihydro-4h-imidazol-4-one with aromatic aldehydes

The reaction of 5,5-bis(hydroxymethyl)creatinine with aromatic aldehydes in the boron trifluoride etherate results in 2-aryl derivatives of 2′-amino-3′-methyl-(1,3-dioxane)-5-spiro-4′-imidazolidin-5′-one.

ChemInform Abstract: Palladium‐Catalyzed Novel Arylations of Cyclic β‐Bromo α,β‐Unsaturated Aldehydes with Triarylbismuths as Multicoupling Organometallic Nucleophiles.

AbstractAn efficient method is presented for the Pd‐catalyzed cross‐coupling of cyclic bromoalkenes with triarylbismuths to afford the corresponding aryl derivatives.