Phenoxy Derivatives Research Articles

Small Molecule Antivirulents Targeting the Iron-Regulated Heme Oxygenase (HemO) ofP. aeruginosa

Bacteria require iron for survival and virulence and employ several mechanisms including utilization of the host heme containing proteins. The final step in releasing iron is the oxidative cleavage of heme by HemO. A recent computer aided drug design (CADD) study identified several inhibitors of the bacterial HemOs. Herein we report the near complete HN, N, CO, Cα, and Cβ chemical shift assignment of the P. aeruginosa HemO in the absence and presence of inhibitors (E)-3-(4-(phenylamino)phenylcarbamoyl)acrylic acid (3) and (E)-N'-(4-(dimethylamino)benzylidene) diazenecarboximidhydrazide (5). The NMR data confirm that the inhibitors bind within the heme pocket of HemO consistent with in silico molecular dynamic simulations. Both inhibitors and the phenoxy derivative of 3 have activity against P. aeruginosa clinical isolates. Furthermore, 5 showed antimicrobial activity in the in vivo C. elegans curing assay. Thus, targeting virulence mechanisms required within the host is a viable antimicrobial strategy for the development of novel antivirulants.

Designing and Binding Mode Prediction of Juvenile Hormone Analogues as Potential Inhibitor for Galleria mellonella

Virtual screening of chemical databases has become an integral part of ligand design. Docking is one of the most important methods in computer assisted screening. If a three dimensional structure of target receptor is available, along with information regarding nature of the ligand-binding site, ligand-binding mode; the interactions between the ligand and receptor can be studied extensively, in order to design and develop target specific new compounds in a short time period. Juvenile Hormone Analogues, sesqui-terpenoid series of compound act as an insect growth regulator, and presently in use as a potential environment friendly pesticide. Juvenile hormone is the molting hormone responsible for each molt, and involved in a wide range of physiological processes in both developing and mature insect. Designing of various juvenile hormone analogues are new and emerging area to counter the insect problem. In this paper, we report protein-ligand interactions using a standard protocol of docking. We perform screening of synthesized (A-B) and proposed (C-D) series of Juvenile Hormone Analogues with hemolymph binding proteins of Galleria mellonella. Further binding energy profile of all the series have been compared with the phenoxy derivatives of juvenile hormone mimics, as well as natural JH III, in order to design targeted JHAs with improved biological activities. Our proposed series of juvenile hormone analogues exhibit better energy profile over in use phenoxy derivatives.

Ionic liquid mediated synthesis, reactions, and insecticidal activity of 1-[(1H-benzoimidazol-2-yl)amino]spiro[azetidine-4,4'-[4'H]chroman]-2-ones

Ionic liquid mediated synthesis of novel heterocyclic compounds 1-[(1H-benzoimidazol-2-yl)amino]-2'-phenylspiro[azetidine- 4,4'-[4'H]chroman]-2-ones (3) and 1-[(1H-benzoimidazol-2-yl)amino]- 3-chloro-2'-phenylspiro[aze tidine-4,4'-[4'H] chroman]-2-ones (4) was accomplished by condensing substituted 2-hydrazino benzimidazole (1), flavanone (2), and acetyl chloride/chloroacetyl chloride in ionic liquid, [bmim]PF_6 with or without using catalyst in excellent yield (90%--95%). Further, compounds 3 and 4 were acylated with trifluoroacetic anhydride to give N-acylated products (5 and 10); 3 when treated with HCHO and (C_2H_5)_2NH gave Mannich bases (6) and with aldehydes afforded 3-arylidene-2-azetidinone (7). Compounds 4 underwent nucleophilic substitution with (i) KI (Finkelstein reaction) and (ii) phenols to give the corresponding iodo and phenoxy derivatives (8 and 9). The synthesized compounds were characterized by analytical and spectral (IR, ^1 H NMR, ^{13}C NMR, and HRMS) data and evaluated for insecticidal activity against Periplaneta americana using cypermethrin as standard and found to exhibit excellent results.

Aluminum Chloride Activation of Chloro-Boronsubphthalocyanine: a Rapid and Flexible Method for Axial Functionalization with an Expanded Set of Nucleophiles

We have developed a process whereby chloro-boronsubphthalocyanine (Cl-BsubPc) and other BsubPcs are activated to reaction with oxygen, sulfur, and nitrogen based nucleophiles by treatment with aluminum chloride under mild conditions. This allows for the scope of atoms chemically bound to the boron atom to be expanded beyond those derived from the traditional oxygen and carbon based nucleophiles. The successful formation of thiophenoxy and phenylamino derivatives of BsubPc was confirmed spectroscopically and by X-ray crystallography of single crystals. We have proposed a detailed mechanism for this process based on experimental observation and NMR spectroscopy ((1)H, (11)B, and (27)Al) which involves formation of a complex between a halo-BsubPc and AlCl(3) (which we denote BsubPc(Cl)·Al(Cl')(3)). Our observations indicate that the action of phenol on BsubPc(Cl)·Al(Cl')(3) does not involve direct reaction at the boron atom; rather phenol first reacts at the aluminum atom along the way to the formation of a new intermediate complex BsubPc(OPh)·Al(O'Ph)(3). The consequence is that the rate of this process is independent of the nature of the starting BsubPc. Cl-BsubPc and Br-BsubPc as well as BsubPcs with peripheral substitutents all react to form their respective phenoxy derivatives at the same rate. Quenching of BsubPc(OPh)·Al(O'Ph)(3) with a Lewis base ultimately produces a new bond between the phenol nucleophile and the boron atom of the BsubPc.

β-Elimination-Immune PCcarbeneP Iridium Complexes via Double C–H Activation: Ligand–Metal Cooperation in Hydrogen Activation

The synthesis of two members of a new PCP pincer ligand family and their complexation with iridium has been developed. Double C–H activation results in a ligand anchored by a carbene donor; hydrogen reversibly adds to the (PCcarbeneP)IrCl complexes 3R (R = iPr, tBu). Aryl, amido, and phenoxy derivatives are available from the chlorides via salt metathesis. These compounds add H2 and eliminate H–X; the iridium compound is trapped as a PCalkylP iridium polyhydride.

Synthesis and characterization of silicon phthalocyanines bearing axial phenoxyl groups for attachment to semiconducting metal oxides

A series of axial phenoxy substituted octabutoxy silicon phthalocyanines bearing ethyl carboxylic ester and diethyl phosphonate groups have been prepared from the corresponding phenols in pyridine. Axial bis-hydroxy silicon phthalocyanine was prepared using an adaptation of a reported protocol [1, 2] from the octabutoxy free-base phthalocyanine. The phenols bear either carboxylic ester or phosphonate groups, which upon deprotection can serve as anchoring groups for attaching the phthalocyanines to semiconducting metal oxides used in dye sensitized solar cells (DSSCs). All the phthalocyanines of the series absorb in the near infra-red region: 758–776 nm. The first oxidation potential for each phenoxy derivative occurs near 0.55 V vs. SCE as measured by cyclic voltammetry, with all falling within a 10 mV range. This indicates that these dyes will have sufficient energy in the photo-excited state to drive the reduction of protons to hydrogen. Taking into account the absorption and electrochemical potentials, these dyes are promising candidates for use in dual-threshold photo-electrochemical cells.

Raman spectroscopic characteristics of octa-substituted bis(phthalocyaninato) rare earth complexes peripherally substituted with (4-methoxy)phenoxy derivatives

The Raman spectroscopic data in the range 500–1800 cm −1 for a series of 15 rare earth double-deckers with tervalent rare earths M III[Pc(MeOPhO) 8] 2 (M = Y, La, …, Lu, except Ce, Pr and Pm), reduced state HPr[Pc(MeOPhO) 8] 2 and intermediate-valent cerium Ce[Pc(MeOPhO) 8] 2 have been collected using laser excitation source emitting at 632.8 nm. With excitation at 632.8 nm, which is in close resonance with the main Q absorption band of the phthalocyanine ligand, typical Raman marker bands of the monoanion radical [Pc(MeOPhO) 8] − were observed at 1500–1528 cm −1 as very strong bands resulting from the coupling of pyrrole C C and aza C N stretchings. For Ce[Pc(MeOPhO) 8] 2 and HPr[Pc(MeOPhO) 8] 2, a very strong band at 1499 cm −1 with contributions from both pyrrole C C and aza C N stretchings and also isoindole stretching was the marker Raman band of [Pc(MeOPhO) 8] 2−. In addition, the influence of ionic radius of the rare earth metal and substituent species on the Raman scatting characteristics of sandwich-type compounds has also been tentatively studied.

ChemInform Abstract: Synthesis of Biologically Active Phenoxy Derivatives of Substituted Benzothiazole Organophosphates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Application of the TMSOTf-AgClO4 Activator System to the Synthesis of Novel, Potent, C-10 Phenoxy Derivatives of Dihydroartemisinin.

ChemInform Abstract: Application of the TMSOTf-AgClO4 Activator System to the Synthesis of Novel, Potent, C-10 Phenoxy Derivatives of Dihydroartemisinin.

Synthesis of biologically active phenoxy derivatives of substituted benzothiazole organophosphates

AbstractThe reaction of S‐(phenyl benzothiazolyl‐2)phosphorodichloridothioate/phosphorodichloridodithioate with 2 mol of phenol/4‐chlorophenol/4‐nitrophenol in the presence of stoichiometric amounts of triethylamine in dry THF/CH2Cl2 has afforded a series of the corresponding organophosphate phenoxy derivatives (1a, 1b, 2a, 2b, and 3a, 3b). Plausible structures have been proposed on the basis of elemental analysis, IR, 1H NMR, 31P NMR, and mass spectral studies. The antibacterial activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (−ve). The antifungal activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. The results indicate that organophosphate phenoxy derivatives are found more active than the parent compounds. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:84–88, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20582

Rational Design of 5-Phenyl-3-isoxazolecarboxylic Acid Ethyl Esters as Growth Inhibitors of Mycobacterium tuberculosis. A Potent and Selective Series for Further Drug Development

New antituberculosis (anti-TB) drugs are urgently needed to shorten the 6-12 month treatment regimen and especially to battle drug-resistant Mycobacterium tuberculosis (Mtb) strains. In this study, we have continued our efforts to develop isoxazole-based anti-TB compounds by applying rational drug design approach. The biological activity and the structure-activity relationships (SAR) for a designed series of 5-phenyl-3-isoxazolecarboxylic acid ethyl ester derived anti-TB compounds were investigated. Several compounds were found to exhibit nanomolar activity against the replicating bacteria (R-TB) and low micromolar activity against the nonreplicating bacteria (NRP-TB). The series showed excellent selectivity toward Mtb, and in general, no cytotoxicity was observed in Vero cells (IC(50) > 128 muM). Notably, selected compounds also retained their activity against isoniazid (INH), rifampin (RMP), and streptomycin (SM) resistant Mtb strains. Hence, benzyloxy, benzylamino, and phenoxy derivatives of 5-phenyl-3-isoxazolecarboxylic acid ethyl esters represent a highly potent, selective, and versatile series of anti-TB compounds and as such present attractive lead compounds for further TB drug development.

Synthesis and photochemical properties of phenoxy derivatives of anthra[2,3-b]furan-5,10-dione

Nucleophilic replacement of the hydroxy groups in ethyl 4,11-dihydroxy-2-methyl-5,10-dioxo-5,10-dihydroanthra[2,3-b]furan-3-carboxylate by chlorine upon treatment with phosphorus acid chlorides gave the corresponding 4(11)-chloro derivatives which were converted into photochromic ethyl 4(11)-phenoxy-2-methyl-5,10-dioxo-5,10-dihydroanthra[2,3-b]furan-3-carboxylates. Photoinduced decomposition of the latter leads to the formation of phenol and fluorescent hydroxyanthra[2,3-b]furandiones.

Nucleophilic heteroaromatic substitution: Kinetics of the reactions of nitropyridines with aliphatic amines in dipolar aprotic solvents

AbstractRate data are reported for the reactions of 2‐chloro‐5‐nitropyridine 2a, 2‐chloro‐3‐nitropyridine 2b, and the corresponding 2‐phenoxy derivatives 2c with n‐butylamine, pyrrolidine and piperidine and 2d with n‐butylamine and pyrrolidine in dimethyl sulfoxide (DMSO) as solvent. The same reactions in acetonitrile had been reported earlier (Crampton et al., Eur J Org Chem 2007, 1378–1383). Values in these solvents are compared with those of 2,4‐dinitrochlorobenzene 3a, 2,6‐dinitrochlorobenzene 3b, and the corresponding nitroactivated diphenyl ethers 3c and 3d. Reactions with n‐butylamine in both solvents gave values of kobs, which increase linearly with amine concentration indicating that nucleophilic attack is rate limiting. The only exception is the reactions in acetonitrile with 2c where base catalysis was observed. Values of k1, the rate constant for the nucleophilic attack, decrease in the order pyrrolidine > piperidine > n‐butylamine. In acetonitrile, kinetic data show that k/k ratios are more than unity while the inverse is the case in DMSO. With the phenoxy derivatives, substitution was the only process observed. Base catalysis detected in the reactions of the 1‐phenoxy derivatives is attributed to rate‐limiting deprotonation of the initially formed zwitterionic intermediate. Our results shed more light on fundamental aspects of activation, hydrogen bonding, and steric effects associated with an aza or a nitro group in the molecules investigated as it affects the nucleophilic aromatic substitution (SNAr) reaction pathways. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 125–135, 2008

Electrochemical and spectroelectrochemical characterization of the phthalocyanines with pentafluorobenzyloxy substituents

The solution redox properties and spectroelectrochemical investigation of the novel metal-free, zinc, nickel and cobalt phthalocyanines with tetra-pentafluorobenzyloxy substituents at the periphery were studied using various electrochemical and spectroelectrochemical measurements. Cyclic voltammetry and differential pulse voltammetry studies show that while Ni(II), Zn(II) and free-phthalocyanines give up to two reduction and two oxidation processes having ligand-based diffusion controlled reversible one-electron electron transfer characters, Co(II) phthalocyanine represents one ligand-based oxidation, one metal-based reduction and one ligand-based reduction processes having diffusion controlled reversible one-electron transfer characters. Assignments of the redox couples are also confirmed by spectroelectrochemical measurements. Reduction potentials of all complexes shift to positive potentials due to the electron withdrawing tetra-pentafluorobenzyloxy substituents compared with those of the phthalocyanines bearing phenoxy derivatives. A linear variation of the first reduction and oxidation potentials versus ze/ r has been obtained for zinc and nickel phthalocyanines.

Synthesis of Thieno[2,3-b]Pyridinones Acting as Cytoprotectants and as Inhibitors of [3H]Glycine Binding to the N-Methyl-d-aspartate (NMDA) Receptor

The standard glycine site antagonist of the N-methyl-D-aspartate (NMDA) receptor, 3-phenyl-4-hydroxyquinolin-2(1H)-one (21), was used as a template for bioisostere benzene/thiophene exchange. Phenylacetylation of aminothiophene carboxylic acid methyl esters and subsequent cyclization delivered the three possible thienopyridinone isomers. 4-Hydroxy-5-phenylthieno[2,3-b]pyridin-6(7H)-one (3a), with the shortest distance between the sulfur and the nitrogen atom, was the most potent isomer (K(i) against the binding of [(3)H]glycine to rat membranes 16 microM), comparable in potency to the model quinolinone (21, 12 microM). Replacement of the phenyl substituent of 21 by a 2-thienyl residue resulted in a 2-5-fold loss in potency and was abandoned. In the thieno part of the thienopyridinone nucleus, the most successful substituents were halogen (Cl or Br) close to the sulfur atom and short alkyl chains at the other position, resulting in 7h, 8h, 8i, and 8m, with K(i) values between 5.8 and 10.5 nM. Introduction of a 3'-phenoxy moiety yielded several compounds with still higher potencies (18h, 18i, 18l, and 18m; K(i) between 1.1 and 2.0 nM). Quantitative structure-activity relationship (QSAR) calculations resulted in a consistent interpretation of the potencies of most compounds. Several of these 3'-phenoxy derivatives protected mouse fibroblast cell lines with transfected NMDA receptors from glutamate-induced toxicity. In addition, we report in vivo results for four of these compounds.

Infrared spectroscopic characteristics of octa-substituted bis(phthalocyaninato) rare earth complexes peripherally substituted with (4-methoxy)phenoxy derivatives

The infrared (IR) spectroscopic data for a series of 15 rare earth double-deckers M[Pc(MeOPhO) 8] 2 [M = Y, La, …, Lu, except Pm; H 2Pc = 2, 3, 9, 10, 16, 17, 23, 24-octakis(4-methoxyphenoxy)phthalocyanine] with tervalent rare earths M III[Pc(MeOPhO) 8] 2 (M = Y, La, …, Lu except Ce and Pm) and intermediate-valent cerium Ce[Pc(MeOPhO) 8] 2 have been collected with resolution of 2 cm −1. For M III[Pc(MeOPhO) 8] 2, typical IR marker band of the monoradical anion Pc(MeOPhO) 8 − shows characteristic absorption band whose frequency linearly varies in the range from 1313 cm −1 as a weak band for La[Pc(MeOPhO) 8] 2 to 1324 cm −1 as a medium band for Lu[Pc(MeOPhO) 8] 2 along with the decrease of rare earth ionic size. For Ce[Pc(MeOPhO) 8] 2, a weak band at 1324 cm −1 with contribution from pyrrole stretching was the marker IR band of phthalocyanine dianion Pc 2−. In conclusion, all the metal size-dependent IR absorptions should be contributed primarily from the vibrations of pyrrole, isoindole stretching, breathing or deformation or aza stretching of the Pc ring.

Synthesis and Antimicrobial Activity of Some New 2‐Methyl‐5‐nitroimidazole Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Experimental and theoretical study of 2,5-diaryloxazoles whose aryl are para-substituted phenyl groups

Absorption and emission properties of some phenoxy derivatives of diphenyloxazole (PPO) are presented and discussed. The photophysical properties reflect a dependence on the substituted 2 or 5 position of the oxazole ring. The experimental data were correlated with molecular parameters such as molecular flexibility, electronic structure and the singlet–triplet gap. The substitution with heteroatomic-bridged phenyls maintains the same frontier orbitals ( m, m + 1) as in the parent compound, but introduces a new molecular orbital, m − 1, located on the terminal phenyl. The presence of the so-called band B in the absorption spectra of some diaryloxazoles was attributed to the m − 1 → m + 1 transition participating to the second excited state wave function. The other main component of this state, the m → m + 2 transition, was found to have a forbidden character, explaining the lack or the low intensity of band B. The decrease of the fluorescence quantum yield subsequent to substitution of PPO with phenoxy fragments was found to be due to the enhanced molecular flexibility comparing to PPO. The differences between the 2- or 5-substituted derivatives were rationalized in terms of a smaller S 1–T 2 gap for the former, thus increasing the rate of the overall nonradiative intersystem crossing processes.

Heterocyclizations of hydroxyketones with two‐coordinated (trimethylsilylamino)phosphines, (Me3Si)2NPESiMe3

AbstractThe reaction of two‐coordinated (trimethylsilylamino)phosphines (Me3Si)2NPESiMe3 1 (E = N) and 2 (E = CH) with hydroxycarbonyl compounds proceeded with four‐ or five‐member heterocyclization to yield derivatives of oxaphosphetane, oxaphospholanes, and oxaphospholes. The reaction rate depends on the structure of hydroxyketones as well as on the type of the two‐coordinated phosphorus compound in accordance with the polarity of the P=N and P=C bonds. Thus, reaction was completed in 30 min in the case of the ortho carbonyl phenoxy derivatives with the phosphine 1, but required 2 h in the case of the alkyl hydroxy carbonyls. All reactions with the phosphine 2 took about 24 h. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:413–417, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20033

Synthesis and antimicrobial activity of some new 2-methyl-5-nitroimidazole derivatives

Amines and phenoxy derivatives of 1,(3'-chloro-2'-hydroxypropyl)-2,methyl-5,-nitroimidazole were synthesized by reacting 1-(3'-chloro-2'-hydroxypropyl)-2-nietliyl-5-nitroimidazole with appropriate amines and phenols. These compounds were characterized by spectral and elemental analyses. All the compounds were screened for their antimicrobial activity.