Ring Carbonyl Research Articles

Cycloadditions of 1-iminylphosphirane complexes with allenes

A cascade carbonylative ring expansion and [2 + 2]/[4 + 2] cycloaddition of strained 1-iminylphosphirane complexes with aryl allenes were reported. The carbonylative ring expansion of 1-iminylphosphirane complexes provides an azaphosphacyclohexone complex intermediate with a CP double bond. The following [2 + 2] or dearomatic [4 + 2] cycloaddition of this intermediate with allenes is modulated by the aryl substituents on the imino carbon. The regioselective [2 + 2] cycloaddition with 1,1-diarylallene provides an entry to bicyclo[4.2.0]octan-4-one skeletons featuring a four-membered phosphacyclobutane moiety. While dearomatic [4 + 2] cycloaddition was preferred with less aromatic naphthalene and yielded octahydrochrysene skeleton containing heteroatoms.

Design, synthesis and in vitro bioactivity of mixed ligand Ru(II) complexes bearing the fluoroquinolone antibacterial agents

Mixed ligand Ru(II) phenanthroline complexes of the type [Ru(1,10-phen)2Flq]ClO4 (RPFlq-1-3) and “piano-stool”-type Ru(II) arene complexes [Ru(η6-p-cymene)Cl(Flq)] (RAFlq-1-3), where Flq = fluoroquinolone, have been synthesized, characterized and studied for their anticancer potential. DFT calculations were in line with the proposed structures, wherein the fluoroquinolones are coordinated to the metal through the ring carbonyl and one of the carboxylic oxygen atoms in a bidentate fashion. Binding efficacies of the synthesized complexes with bovine serum albumin (BSA) and CT-DNA were studied spectroscopically, and it has been established that the arene complexes, though have moderate binding propensities to CT-DNA (Kb = 0.8–1.7 × 103 M−1), have 102–103-fold better binding efficacies toward BSA (Ka = 3.2 × 105–2.1 × 106 M−1) due to the presence of the hydrophobic arene moiety. These results further prompted a study in their in vitro cytotoxicity assay on A-549 non-small cell lung cancer and MCF7 breast cancer cell lines. Furthermore, gene expression studies on BAX and BCL-2 genes and FACS analysis confirmed apoptosis as the mode of cell death.

Difluoromethylene at the γ-Lactam α-Position Improves 11-Deoxy-8-aza-PGE1 Series EP4 Receptor Binding and Activity: 11-Deoxy-10,10-difluoro-8-aza-PGE1 Analog (KMN-159) as a Potent EP4 Agonist.

A series of small-molecule full agonists of the prostaglandin E2 type 4 (EP4) receptor have been generated and evaluated for binding affinity and cellular potency. KMN-80 and its gem-difluoro analog KMN-159 possess high selectivity relative to other prostanoid receptors. Difluoro substitution is positioned alpha to the lactam ring carbonyl and results in KMN-159's fivefold increase in potency versus KMN-80. The two analogs exhibit electronic and conformational variations, including altered nitrogen hybridization and lactam ring puckering, that may drive the observed difluoro-associated increased potency within this four-compound series.

Ethyl 2-(4-benzyl-3-methyl-6-oxo-1,6-dihydropyridazin-1-yl)acetate: crystal structure and Hirshfeld surface analysis.

The title compound, C16H18N2O3, is constructed about a central oxopyridazinyl ring (r.m.s. deviation = 0.0047 Å), which is connected to an ethyl-acetate group at the N atom closest to the carbonyl group, and benzyl and methyl groups second furthest and furthest from the carbonyl group, respectively. An approximately orthogonal relationship exists between the oxopyridazinyl ring and the best plane through the ethyl-acetate group [dihedral angle = 77.48 (3)°]; the latter lies to one side of the central plane [the Nr-Nr-Cm-Cc (r = ring, m = methyl-ene, c = carbon-yl) torsion angle being 104.34 (9)°]. In the crystal, both H atoms of the N-bound methyl-ene group form methyl-ene-C-H⋯O(ring carbon-yl) or N(pyridazin-yl) inter-actions, resulting in the formation of a supra-molecular tape along the a-axis direction. The tapes are assembled into a three-dimensional architecture by methyl- and phenyl-C-H⋯O(ring carbon-yl) and phenyl-C-H⋯O(ester carbon-yl) inter-actions. The analysis of the calculated Hirshfeld surface indicates the dominance of H⋯H contacts to the overall surface (i.e. 52.2%). Reflecting other identified points of contact between mol-ecules noted above, O⋯H/H⋯O (23.3%), C⋯H/H⋯C (14.7%) and N⋯H/H⋯N (6.6%) contacts also make significant contributions to the surface.

Ir‐Catalyzed Asymmetric Hydrogenation of α‐Alkylidene β‐Lactams and Cyclobutanones

Chiral β‐lactams and cyclobutanones are present in numerous natural and pharmaceutical products. The stereoselective construction of chiral four‐membered cyclic compounds is an ongoing challenge for the chemical community. Herein, we report a highly stereocontrolled construction of four‐membered ring (mini‐sized) β‐lactams and cyclobutanones via an Ir/In‐BiphPHOX‐catalyzed asymmetric hydrogenation, providing the corresponding optically active four‐membered ring carbonyl products bearing an α‐chiral carbon center with excellent yields (up to 99%) and enantioselectivities (up to 98%) under mild reaction conditions (1.0—2.5 bar H2 for 1.0—10 h). The reaction presents wide substrate scope. Diverse transformations of the catalyzed products were also conducted to show the potential utility of this protocol.

Synthesis and characterization of unique new lithium, sodium and potassium coordination polymers

Abstract Five new alkali metal coordination compounds [Li(NPG)](1a), [Na(NPG)2]⋅2H2O(2a), [C8H5KO4](3a), [Li(NPA)2H2O](1b) and [Na(NPA)2](2b) wherein (NPG = N-phthaloyl glycine, NPA = N-phthaloyl-s-alanine) have been synthesized and characterized by means of X ray single crystal analysis, Infrared spectroscopy (IR), Thermogravimetric analysis (TGA) and Florescence spectroscopy. The compounds 1a, 2a, 3a and 2b showed metal directed self-assembly supramolecular network structures. The crystal structure of compounds 1a and 1b showed distorted tetrahedral geometry with coordination number 4 around lithium. The carboxylate coordination modes were η2µ3and η1µ1 in 1a and 1b respectively. The compounds 2a and 2b exhibited distorted octahedral geometry with coordination number 6 around sodium. The carboxylate coordination mode in 2a and 2b is η2µ2. The objective was to synthesize potassium complex [K(NPG)], but N-phthaloyl glycine was hydrolysed due to exothermic reaction in the presence of strong base, resulted, the formation of 3a. The multiple coordination modes of alkali metal ions to the carboxylate and ring carbonyl oxygen atoms of NPG and NPA produced unique three dimensional architectures. The compounds 1b and 2b showed two strong fluorescence emissions enhancement (blue emission maxima) with greater intensity comparative to NPA, while the compounds 1a and 2a showed two weak fluorescence emissions with less intensity comparative to ligand (NPG). The base hydrolysis of NPG with in the compound 3a resulted the change of ligand based fluorochrome, which produced different shape emission spectrum as compared to other compounds.

Biophytum sensitivum nanomedicine reduces cell viability and nitrite production in prostate cancer cells

Phytomedicine research received tremendous attention for novel therapeutic agent due to their safety and low cost. We assessed a novel nanoformulation of Biophytum sensitivum (BS), natural flavonoids for their improved efficacy and superior bioavailability against crude extract for prostate cancer cells (PC3). We prepared a nanomedicine of BS by nanoprecipitation method and size analysis via DLS and SEM revealed a range of 100–118 nm and surface zeta potential as −9.77 mV. FTIR was performed to evaluate functional for presence of carbonyl and aromatic rings, respectively. Human PC3 cells showed concentration at 0.5, 0.8, and 1 mg/ml dependent cytotoxicity 22, 39, and 56% for 24 h, whereas 43, 41, and 67% for 48 h of BS nanomedicine compared with crude 11, 22, and 53% for 24 h and 38, 31, and 60% for 48 h, respectively. Haemocompatibility of BS nanomedicine at the concentration of 0.5, 0.8, and 1 mg/ml did not show blood aggregation. Cellular uptake was confirmed using rhodamine-conjugated BS nanomedicine for 48 h. Interestingly, BS nanomedicine 1 mg/ml decreases the nitrite productions in PC3 cells. Collectively, BS nanomedicine has the potential anti-cancer agents with biocompatible and enhanced efficacy can be beneficial for the treatment of prostate cancer

Photo‐oxidation of poly(2,6‐dimethyl‐1,4‐phenylene oxide): A reinvestigation

ABSTRACTReinvestigation of poly(2,6‐dimethyl‐1,4‐phenylene oxide) photodegradation at wavelengths > 290 nm shows that both methyl groups and aromatic rings are sites of oxidation with their relative rates dependent on exposure conditions, based on infrared spectroscopy. The methyl group loss is linear with exposure and apparently proceeds by direct abstraction of a benzylic hydrogen by oxygen. The aromatic ring loss and carbonyl growth in the IR spectra appear to be auto‐accelerating and seem to proceed by electron transfer to oxygen, either sensitized or through a direct reaction with oxygen, and recombination of the polymer radical cation and superoxide to result in oxygen addition to the ring. Molecular weight loss in solution occurs to a significant degree only in the presence of oxygen, even in the presence of a hydrogen‐donating solvent, indicating that aryl ether photolysis is not a major pathway. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2318–2331

Conformational analysis of N→BH3, N→BF3, and N-CH3+complexes with ibuprofen-derivative amides

The synthesis and structural characterization of novel amine-borane adducts of ibuprofen derivatives are presented. The changes of the electron density on the carbonyl and pyridine ring after formation of N→BH3, N→BF3, and N-CH3+ have been confirmed by 1H, 11B, 13C, and 19F NMR, further supported by homonuclear and heteronuclear correlations. Moreover, electrostatic interactions —H+···−F and the nonclassical H+···−H— were identified by NMR spectra. The analysis of the resulting molecular structures offered insights on the 2-aminopyridine N→B adducts. The N→BH3 adduct formed a single molecular arrangement, both in C6D6 and CDCl3. The same behavior was observed for the N→BF3 adduct in CDCl3. However, two conformers of this adduct were detected in C6D6. All adduct geometries were corroborated by density functional theory computational calculations.

Ethyl 6-(4-chlorophenyl)-2,2-dimethyl-4-oxo-3,4-dihydro-2H-pyran-5-carboxylate

The title compound, C16H17ClO4, is a derivative of 3,4-dihydro-2H-pyran-4-one in which the root moiety forms a dihedral angle of 49.36 (5)° with the pendent chlorobenzene ring. The crystal structure features weak methyl-C—H...O(ring carbonyl) contacts, leading to an R 2 2(12) ring motif, and benzene-C—H...O(ester) interactions, leading to a supramolecular chain along the b axis, to form a three-dimensional network.

Isolated alkali cation complexes of the antibiotic ionophore nonactin: correlation with crystalline structures.

The antibiotic activity of nonactin is sustained by its ability to transport K+ across lipophilic phases, e.g., the cell membranes. Such a feature can be traced back to a specific ionophoric behavior and to a balanced hydrophobicity modulated by the formation of a cation complex. In this study, the dominant conformations and coordination arrangements in the alkali cation complexes (Na+, K+, Cs+) of nonactin are characterized by means of action vibrational spectroscopy and quantum chemical computations. The low energy conformers of the complexes comprise compact inclusion structures, in which the cation interacts with a varying number of oxygen atoms of the carbonyl and oxolane ring groups of the nonactin macrocycle. The spectroscopy experiments indicate that the three alkali complexes explored are formed in a S4 conformation. This is in contrast with previous crystallography studies, which concluded that the symmetry of the most stable conformer of the complex changes qualitatively with the cation size, from C2 for Na+ to S4 for K+ and Cs+. Computations with different hybrid density functionals lead to contradictory predictions that appear to be quite sensitive to the modelling of the long range interactions in the coordination arrangements. The stabilization of the nonactin-Na+ complex in the C2 or S4 forms emerges as a subtle feature that may be tuned with an appropriate control of the environmental conditions, and constitutes a challenging benchmark to confront novel computational methods for supramolecular systems.

Structural and Spectral (IR, NMR and UV/Visible) Properties of Newly Designed Boronic Acid Derivatives Containing DO3A Sensitive to Uranyl Ion: A DFT and TD-DFT Study

In this study, the structural, electronic and optical properties of DO3A-based boronic acid derivates with and without UO22+ ion are studied by density functional calculations with M062X/6 - 31 g + (d) method, in aqueous media. The quantum chemical properties such as EHOMO, ELUMO, the energy gap (ΔE), chemical potential (μ), hardness (η) are also performed. The theoretical essential UV-Vis. bands of DO3A-UO2(VI)-APB-o are at 392 and 687 nm. DO3A-UO2 (VI)-ABB-o structure has two main bands at 393 and 650 nm. In general, the bathochromic shift occurs and the HOMO-LUMO energy gap decreases to about 2 eV, by binding UO22+ ion in three different media. The notable shifts in NMR spectrums have been found on α-carbon of carbonyl group, ring carbons and amide protons. In IR-spectrums, the prominent peaks belong to BO-H and N-H of amide stretching vibrations of calculated structures.

SPECTRAL CHARACTERIZATION AND BIOCIDAL STUDIES OF 2, 2, 6, 6 -TETRAMETHYLPIPERIDIN-4-ONE AND THEIR PALLADIUM (II) COMPLEX

A binuclear palladium ( II) complex , of the type (Pd 2 (μ - Cl) 2 (L) 4 )Cl 2 ( where L - 2,2',6,6' - tetramethylpiperidin - 4 - one ) have been synthesi s ed and characteri s ed by elemental analysis, FT - IR, UV - Vis, mass, 1 H and 13 C NMR spectra. The ligand containing two coordinating sites , namely ring nitrogen and carbonyl group. The spectral studies revealed that the ligand is monoden t ate in which the ring nitrogen coordinated to palladium ( II) but not the carbonyl group. Electronic spectral data reveal that the complex has square planar geometry. The anticancer studies against the cervical HeLa cell line and antimicrobial activity against Escherichia coli, Staphylococcus aureus, Aspergillus niger and Candida albicans were screene d for Palladium(II) complex(C), Dichloro(1,5 - cyclooctadiene)palladium(II)(M) and 2,2',6,6' - tetramethylpiperidin - 4 - one (L).

Synthesis, stereochemical and biological studies of some N-cyclohexylcarbamoyl -2,6-diarylpiperidin-4-ones

A series of N-cyclohexylcarbamoylpiperidin-4-ones were synthesized by the addition reaction of corresponding piperidin-4-ones with cyclohexylisocyanate in benzene. The structure and stereochemistry of the synthesized N-cyclohexylcarbamoyl -2, 6-diarylpiperidin-4-ones, were established on the basis of their analytical and spectral data (IR, 1H and 13C NMR). 2D NMR spectra (HOMOCOSY, HSQC, HMBC and NOESY) were also recorded to analyze the stereochemistry. In the IR spectra of synthesized compounds, the characteristic absorptions due to ring and amide carbonyl functionalities were observed which evidences the formation of N-cyclohexylcarbamoyl-2, 6-diarylpiperidin-4-ones. NMR spectral results are in line with the proposed structure of the compounds synthesized. Conformational analysis was carried out from the extracted coupling constants and NOESY spectral results. The synthesized compounds were evaluated for their antibacterial and antifungal activities.

Oxidative addition of halogen across an Os-Os or Os-Sb bond: Formation of five-membered osmium-antimony carbonyl rings

Halogenation of the cluster Os3(CO)10(μ-SbPh2)2, 2, with PhICl2 or I2 affords the five-membered metallacyclic rings Os3(Cl)2(CO)10(μ-SbPh2)2, 3d and Os3(I)2(CO)10(μ-SbPh2)2, 3d-I, respectively, via oxidative addition across an OsOs bond. The reaction of 2 with SbPh2Cl or SbPh2H gives the 3,5-fused rings Os3(X)(CO)9(μ-SbPh2)3, (X = Cl, 4a; H, 4b), respectively. Halogenation of 4 with PhICl2 gives the five-membered metallacyclic rings Os3(Cl)(X)(CO)9(SbPh2Cl)(μ-SbPh2)2 (X = Cl, 5a; H, 5b) via oxidative addition across an OsSb bond. The analogous reaction with I2 also results in oxidative addition across an OsSb bond, but this is followed by displacement of SbPh2I to afford a five-membered metallacycle containing a μ-I ligand, viz., Os3(μ-I)(X)(CO)9(μ-SbPh2)2 (X = Cl, 7a, H, 7b).

In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from −0.3 to −0.5V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from −0.3 to −0.5V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

Development of glycine-α-methyl-proline-containing tripeptides with neuroprotective properties

Herein is described the synthesis of novel glycine-α-methyl-proline-containing tripeptides (GPMeX tripeptides namely GPMeR, GPMeK, and GPMeH) with the aim of obtaining derivatives highly stable in human plasma and able to counteract neuroinflammatory processes that are distinctive of neurodegenerative pathologies. The syntheses of GPMeR, GPMeK, and GPMeH were all achieved both by introducing the ProMe residue into the Gly-Pro-Arg (GPR) sequence in place of the native Pro in P2 position and replacing the basic amino acid Arg in P3 position by Lys or His.Results showed that all novel GPMeX tripeptides are stable in human plasma (t1/2 > 51 h) and that GPMeH – generating stable intramolecular H-bond in a C11-turn by interaction of His imidazole ring and Gly carbonyl group – restored physiological levels of nitric oxide deriving from neuronal NOS (nNOS) activity, thus preventing the inflammatory response by suppression of the NF-kB activity and, consequently, the expression of inflammatory genes such as inducibile NOS (iNOS). Therefore, GPMeH could be a lead compound for further development of peptidomimetics able to contrast neuroinflammatory processes.

Five novel spectrophotometric methods for quantitative determination of Prulifloxacin in pure and pharmaceutical formulations

The main objective of this present work is to successfully develop one UV and four visible new spectrophotometric techniques. One UV and four visible spectrophotometric methods have been developed depending on the reactivity of various structural units for instance piperazine ring and tertiary amine and carbonyl group in Prulifloxacin. It is observed that the statistical analysis results of correlation coefficient of each method values are observed to be greater than 0.999 which speaks that the proposed methods have good linearity. The order of sensitivity of the said proposed methods are M1> M2>M5c> M5b> M5a> M4> M3. The % RSD values are observed bellow two for all methods which shows that all the proposed methods are precise. The results of analysis of the pharmaceutical formulations assert that the proposed methods are safely be adopted for routine quality control of Prulifloxacin in bulk and pharmaceutical preparations to yield correct and accurate analysis results

Crystal structure of 1-benzyl-2-hy-droxy-5-oxopyrrolidin-3-yl acetate.

In the title compound, C13H15NO4, the oxopyrrolidin-3-yl ring has an envelope conformation, with the C atom bearing the acetate group being the flap. The acetate and phenyl groups are inclined with respect to the central ring, forming dihedral angles of 50.20 (12) and 87.40 (9)°, respectively, with the least-squares plane through the ring. The dihedral angle between the acetate group and the phenyl ring is 63.22 (8)°, indicating a twisted conformation in the mol­ecule. In the crystal, supra­molecular chains along the b axis are formed by (hy­droxy)O—H⋯O(ring carbon­yl) hydrogen bonds. The chains are consolidated into the three-dimensional architecture by C—H⋯O inter­actions.

Crystal structure of 4-oxo-4H-chromene-3-carb-oxy-lic acid.

In the title compound, C10H6O4, also known as 3-carb­oxy­chromone, the non-H atoms of the chromone ring are essentially coplanar (r.m.s. deviation = 0.0057 Å), with the maximum deviation from their least-squares plane [0.011 (2) Å] being for a pyran C atom. The dihedral angle between the fused ring and plane of the carb­oxy group is 3.06 (2)°. An intra­molecular hydrogen bond is formed between the ring carbonyl O atom and the carb­oxy O—H atom, closing an S(6) loop. In the crystal, mol­ecules are assembled by stacking inter­actions [centroid–centroid distance between the benzene and pyran rings = 3.844 (3) Å] and C—H⋯O hydrogen bonds, generating a three-dimensional network. Short contacts are also observed between the carb­oxy O and C atoms [C=O⋯C=O = 3.002 (3) Å].