[show abstract][hide abstract] ABSTRACT: Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies. Green chemistry uses highly efficient and environmentally benign synthetic protocols to deliver lifesaving medicines, accelerating lead optimization processes in drug discovery, with reduced unnecessary environmental impact. From this view point, it is desirable to use water instead of organic solvents as a reaction medium, since water is safe, abundant and an environmentally benign solvent.
A convenient one-pot method for the efficient synthesis of the novel Zwitterion derivatives 4a-p via a three-component condensation reaction of barbituric acid derivatives 1a,b, dimedone 2, and various aldehydes 3 in the presence of aqueous diethylamine media is described. This new approach is environmentally benign, with clean synthetic procedure, short reaction times and easy work-up procedure which proceeded smoothly to provide excellent yield (88-98%). The synthesized products were characterized by elemental analysis, IR, MS, NMR and CHN analysis. The structure of 4a was further confirmed by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Pbca with alpha = 14.6669 (5) A, b = 18.3084 (6) A, c = 19.0294 (6) A, alpha = 90[ring operator], beta = 90[ring operator], = 90[ring operator], V = 5109.9 (3) A3, and Z = 8. The molecules are packed in crystal structure by weak intermolecular C-H . . .O hydrogen bonding interactions.
An environmentally benign Aldol-Michael protocol for the synthesis of dimedone-barbituric derivatives using aqueous diethylamine medium is achieved.
Chemistry Central Journal 02/2014; 8(1):9. · 1.31 Impact Factor
[show abstract][hide abstract] ABSTRACT: There are two independent mol-ecules in the asymmetric unit of the title compound, C16H17NO4, with similar conformations but some differences in their bond angles. Each mol-ecule adopts a trans configuration with respect to the methyl-idene C=N bond and is twisted with a dihedral angle between the two substituted benzene rings of 80.52 (7)° in one mol-ecule and 83.53 (7)° in the other. All meth-oxy groups are approximately coplanar with the attached benzene rings, with Cmeth-yl-O-C-C torsion angles ranging from -6.7 (2) to 5.07 (19)°. In the crystal, independent mol-ecules are linked together by O-H⋯N and O-H⋯O hydrogen bonds and a π-π inter-action [centroid-centroid distance of 3.6030 (9) Å], forming a dimer. The dimers are further linked by weak C-H⋯O inter-actions and another π-π inter-action [centroid-centroid distance of 3.9452 (9) Å] into layers lying parallel to the ab plane.
[show abstract][hide abstract] ABSTRACT: In the structure of the title salt, C20H20NO(+)·C6H4FO3S(-), the 4-(eth-oxy-phen-yl)ethenyl unit is disordered over two positions with a refined site-occupancy ratio of 0.610 (6):0.390 (6). The cation is nearly planar, the dihedral angle between the quinolinium and benzene rings being 6.7 (4) and 1.7 (7)° for the major and minor components, respectively. The eth-oxy group is essentially coplanar with the benzene ring [C-O-C-Cmethy = 177.1 (8) and 177.8 (12)° for the major and minor components, respectively]. In the crystal, cations and anions are linked into chains along the b-axis direction by C-H⋯Osulfon-yl weak inter-actions. These chains are further connected into sheets parallel to (001) by C-H⋯Osulfon-yl weak inter-actions. The chains are also stacked along the a axis through π-π inter-actions involving the quinolinium and benzene rings [centroid-centroid distances = 3.636 (5) Å for the major component and 3.800 (9) Å for the minor component]. C-H⋯π inter-actions are also present.
[show abstract][hide abstract] ABSTRACT: Photo-induced reactions of bicyclopropylidene (BCP) with para-quinones (p-quinones) including benzoquinones, naphthoquinones and anthraquinones were found to proceed via different cycloaddition pathways and lead to diverse polycyclic products bearing spiropropyl moiety. Photocycloaddition of BCP with benzoquinones gave spirooxetanes as the primary products which upon irradiation were able to rearrange into the spiro[4.5]deca-6,9-diene-2,8-diones as secondary photoproducts. Chemo-selectivity of the photocycloaddition of BCP with naphthoquinones relies largely on the substitution groups linked to the C=C in between the two carbonyl groups to give different types of products. Photoreaction of BCP with 9,10-anthraquinone gave not only the spirooxetane product, but also a novel spiro[indan-1,1'-phthalan]-3'-one product whose formation might be initiated by a transannular attack of the C4 cyclopropyl radical to the para-carbonyl group. Mechanisms involved in the formation of diverse primary or secondary products in the photoreactions of BCP with p-quinones were proposed. Some of the photoreactions also hold potentials as useful synthetic protocol for important spiropolycyclic compounds such as sesquiterpenes.
The Journal of Organic Chemistry 05/2013; · 4.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: Phytochemical investigation on Myrtus communis Linn. afforded myrtucommuacetalone (1) with an unprecedented carbon skeleton and a new phloroglucinol-type compound, myrtucommulone M (2), along with four known constituents 3-6. Their structures were established by extensive analyses of NMR and mass spectral data as well as by single-crystal X-ray diffraction studies. These constituents were evaluated for their ability to modulate the immune response, based on their effects on various components of immune system. Compounds 1 and 5 exhibited significant inhibitory effect against nitric oxide (NO(•)) production. Compound 1 also exhibited significant antiproliferative activity (IC50 < 0.5 μg/mL) against T-cell proliferation. Myricetin (3) exerted a significant inhibition (IC50 = 1.6 μg/mL) on zymosan-stimulated whole blood phagocytes ROS production. Compounds 1 and 3 were active against PMA-stimulated ROS generation.
[show abstract][hide abstract] ABSTRACT: The asymmetric unit of the title compound, C18H18ClN3OS·C2H5OH, comprises a pyrazoline derivative and an ethanol solvent mol-ecule. In the mol-ecule of the pyrazoline derivative, the pyrazole ring adopts an envelope conformation with the C atom bearing the eth-oxy-phenyl substituent as the flap. The dihedral angle between the benzene rings is 74.22 (7)°. The eth-oxy group is coplanar with the attached benzene ring [C-O-C-Cmeth-yl = 175.50 (11)° and r.m.s. deviation = 0.0459 (1) Å for the nine non-H atoms]. In the crystal, the pyrazoline mol-ecules are linked by N-H⋯Oeth-oxy hydrogen bonds into chains along the c axis and are further linked with the solvent ethanol mol-ecules by N-H⋯Oethanol and Oethanol-H⋯S hydrogen bonds. C-H⋯π inter-actions are also present.
[show abstract][hide abstract] ABSTRACT: In the title compound, C14H17N3O2, the mean plane of the 1,8-naphthyridine ring system (r.m.s deviation = 0.020 Å) forms a dihedral angle of 23.4 (1)° with the acetamide moiety (r.m.s deviation = 0.001 Å). The mol-ecular structure is stabilized by an intra-molecular O-H⋯N hydrogen bond, which generates an S(5) ring motif. In the crystal, mol-ecules are linked into inversion dimers by pairs of N-H⋯O hydrogen bonds, generating 18-membered R 2 (2)(18) ring motifs.
[show abstract][hide abstract] ABSTRACT: In the title compound, C13H12O5, the mean plane of the 2H-chromene ring system (r.m.s deviation = 0.026 Å) forms a dihedral angle of 81.71 (6)° with the mean plane of ethyl 2-hy-droxy-acetate moiety (r.m.s deviation = 0.034 Å). In the crystal, C-H⋯O hydrogen bonds result in the formation of zigzag layers parallel to the bc plane.
[show abstract][hide abstract] ABSTRACT: The asymmetric unit of the title compound, CHNO, contains two mol-ecules ( and ), which exist in conformations with respect to their C=N double bond. The dihedral angles between the benzene ring and the pendant hy-droxy-carbamimidoyl and acetamide groups are 28.58 (7) and 1.30 (5)°, respectively, in mol-ecule and 25.04 (7) and 27.85 (9)°, respectively, in mol-ecule . An intra-molecular N-H⋯N hydrogen bond generates an (6) ring in both mol-ecules. Mol-ecule also features an intra-molecular C-H⋯O inter-action, which closes an (6) ring. In the crystal, the mol-ecules are linked by N-H⋯O, N-H⋯N, O-H⋯O, O-H⋯N, C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π inter-actions, generating a three-dimensional network.
[show abstract][hide abstract] ABSTRACT: In the title benzene-solvated heteroleptic lithium complex, [Li(CHPS)(CHN)]·CH, the Li ion is four-coordinated in a distorted tetra-hedral geometry by two S atoms and two N atoms of the two chelating ligands, bis-(diphenyl-thio-phosphino-yl)methyl and 2,2'-bipyridine. The 2,2'-bipyridine mol-ecule is slightly twisted with a dihedral angle between the pyridine rings of 7.35 (12)°. Intra-molecular C-H⋯S hydrogen bonds are present. In the crystal, mol-ecules are stacked along the axis by π-π inter-actions, with centroid-centroid distances of 3.6021 (15) and 3.6401 (16) Å. The crystal structure also features weak C-H⋯π inter-actions.
[show abstract][hide abstract] ABSTRACT: The asymmetric unit of the title compound, 2CHN ·CO , contains two 3,5-diamino-4-1,2,4-triazolium cations and one squarate dianion. The squaric acid mol-ecule donated one H atom to each of the two 3,5-diamino-1,2,4-triazole mol-ecules at their N atoms. The squaric acid dianion has four C-O bonds which are shorter than a normal single C-O bond (1.426 Å) and are slightly longer than a normal C=O bond (1.23 Å), which indicates the degree of electron delocalization in the dianion. In the crystal, the cations and dianions are linked by N-H⋯N and N-H⋯O hydrogen bonds into a three-dimensional network.
[show abstract][hide abstract] ABSTRACT: Synthesis and characterization of (1)-1-(4-chlorophenyl)-N-hydroxy-3-(1-imidazol-1-yl)propan-1-imine (4) are reported. X-ray crystal structure of the title oxime 4 confirmed its assigned (E)-configuration. The compound crystallizes in the monoclinic space group 21/c with (3) , (2) , (3) , , (2)°, , (5) , and . The molecules are packed in crystal structure by weak intermolecular hydrogen bonding interactions. Compound 4 is a useful intermediate for the synthesis of new imidazole-containing antifungal agents.
[show abstract][hide abstract] ABSTRACT: Four pyrazole compounds, 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde (1), 5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde (2), 1-[5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone (3) and 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]propan-1-one (4), have been prepared by condensing chalcones with hydrazine hydrate in the presence of aliphatic acids, namely formic acid, acetic acid and propionic acid. The structures were characterized by X-ray single crystal structure determination. The dihedral angles formed between the pyrazole and the fluoro-substituted rings are 4.64(7)° in 1, 5.3(4)° in 2 and 4.89(6)° in 3. In 4, the corresponding angles for molecules A and molecules B are 10.53(10)° and 9.78(10)°, respectively.
[show abstract][hide abstract] ABSTRACT: Flavodoxins, which exist widely in microorganisms, have been found in various pathways with multiple physiological functions. The flavodoxin (Fld) containing the cofactor flavin mononucleotide (FMN) from sulfur-reducing bacteria Desulfovibrio gigas (D. gigas) is a short-chain enzyme that comprises 146 residues with a molecular mass of 15 kDa and plays important roles in the electron-transfer chain. To investigate its structure, we purified this Fld directly from anaerobically grown D. gigas cells. The crystal structure of Fld, determined at resolution 1.3 Å, is a dimer with two FMN packing in an orientation head to head at a distance of 17 Å, which generates a long and connected negatively charged region. Two loops, Thr59-Asp63 and Asp95-Tyr100, are located in the negatively charged region and between two FMN, and are structurally dynamic. An analysis of each monomer shows that the structure of Fld is in a semiquinone state; the positions of FMN and the surrounding residues in the active site deviate. The crystal structure of Fld from D. gigas agrees with a dimeric form in the solution state. The dimerization area, dynamic characteristics and structure variations between monomers enable us to identify a possible binding area for its functional partners.
International Journal of Molecular Sciences 01/2013; 14(1):1667-83. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: The title dammarane tritepene, 3α,20(S)-dihy-droxy-dammar-24-ene, which crystallized out in a hydrated form, C(30)H(52)O(2).1.075H(2)O, was isolated from the Aglaia eximia bark. The three cyclo-hexane rings adopt chair conformations. The cyclo-pentane has an envelope conformation with the quaternary C at position 14 as the flap atom with the maximum deviation of 0.288 (2) Å. The methyl-heptene side chain is disordered over two positions with 0.505 (1):0.495 (1) site occupancies and is axially attached with an (+)-syn-clinal conformation. The hydroxyl group at position 3 of dammarane is in a different conformation to the corresponding hydroxyl in Dammarenediol II. In the crystal, the dammarane and water mol-ecules are linked by O(Dammarane)-H⋯O(water) and O(water)-H⋯O(Dammarane) hydrogen bonds into a three-dimensional network.
[show abstract][hide abstract] ABSTRACT: The title compound, C(16)H(13)Cl(2)F(3)N(2), exists in an E conformation with respect to the C=N bond [1.2952 (11) Å] and the C-N-N=C torsion angle is 175.65 (8)°. The dihedral angle between the benzene rings is 42.09 (4)°. An intra-molecular C-H⋯F hydrogen bond generates an S(6) ring. In the crystal, the mol-ecules are linked into  chains by C-H⋯F hydrogen bonds.
[show abstract][hide abstract] ABSTRACT: A series of Zn(II) ferrocenylthiosemicarbazones complexes derived from thiosemicarbazide and 4-methyl-, 4-ethyl-, and 4-phenyl-3-thiosemicarbazide were evaluated for their DNA binding propensity and chemical nuclease activity. The equilibrium binding constants, Kb, of the complexes for binding with calf thymus
DNA (CT DNA) were in the range of 0.68 × 103 to 2.8 × 104 M−1. The complexes do not intercalate into the nucleobases of CT DNA, as evident from viscosity measurements. They exhibit efficient nuclease activity in the absence of an activating agent and cleave supercoiled DNA into nicked and linear circular forms of DNA at very low concentrations.
Synthesis and Reactivity in Inorganic Metal-Organic and Nano-Metal Chemistry 10/2012; · 0.50 Impact Factor