Reactions of γ-sultones containing a polycyclic fragment

Hydrolytic cleavage of cage γ-sultones have been studied. Alkaline hydrolysis of homoadamantane γ-sultone leads to the formation of sulfonates with erythro configuration. The reduction of homoadamantane γ-sultone with LiAlH₄–AlCl₃ yields desulfurization and deoxygenation products.     

Synthesis of a benzoxazine monomer containing maleimide and allyloxy groups

A novel benzoxazine monomer 3-（4-allyloxy）phenyl-3,4-dihydro-2H-6-（N-maleimido）-l,3-benzoxazine （AMB） was synthesized and structure was confirmed by FT-IR, 1H NMR. Thermal analysis （DSC） of AMB showed the introduction of allyloxy group melting point and exhibited a narrow and symmetric curing exothermic window.     

Mechanism of cleaving DNA through hydrolysis of a novel complex of Mg containing dien ligand

A series of elements necessary for life bodies, such as Mg, Cu, Mn, Fe, Co, Zn etc, arechosen as ceflter ions of complexes, because most of them act as active centers ofenZymes and auxiliary factors. We select dien as ligand because nitrogen, especiallymuti-nitrogen coordination is general in natural enzymes and simulated systems,furthermore dien has structural flexibility.The complexes of Mg containing dien and the activity of cleaving DNAA series of metals, such as Mg, Mn, Fe, Co, Ni, …     

Stereo-regulated synthesis of peptides containing a β-trifluoromethyl-β-amino acid

For the chemical conversions of a β-trifluoromethyl-β-amino acid ((S)-4,4,4-trifluoro-3-aminobutyric acid, 1), such as the N-terminus protection with benzyloxycarbonyl or tert-butoxycarbonyl group, the C-terminus protection with benzyl or tert-butyl group, and peptide elongation at the both termini, highly practical protocols were established. Through these conversions, the stereochemistry of 1 and/or its condensation counterpart was maintained. Because the protocols developed here are indispensable for the application of 1 in peptide engineering, they would expand the utility of 1 and its derivatives.     

Synthesis and thermal stability of a novel phosphorus-nitrogen containing intumescent flame retardant

A novel phosphorus-nitrogen containing intumescent flame retardant （P-N IFR） was prepared via the reaction of dichlor-opentate with N-methylaniline. The structure of the product was confirmed by ^1H NMR, ^31p NMR, MS and IR. TGA analysis showed it has effective thermal stability.     

Nucleation of β-hairpin structure in a pyrrole amino acid containing peptide

Synthesis and conformational studies of two short peptides containing pyrrole amino acids (1, Paa), Boc-Paa-Paa-d-Pro-Gly-Xaa-Paa-Paa-OMe (2: Xaa=Ala; 3: Xaa=Val), were carried out in which it was established that replacement of Ala in 2 with a Val residue helps peptide 3 to adopt a well-defined β-hairpin conformation in a nonpolar solvent, like CDCl₃.     

Solution structure of a DNA duplex containing a guanine-difluorotoluene pair: a wobble pair without hydrogen bonding?

The incorporation of synthetic nucleoside analogues into DNA duplexes provides a unique opportunity to probe both structure and function of nucleic acids. We used 1H and 19F NMR and molecular dynamics calculations to determine the solution structures of two similar DNA decamer duplexes, one containing a central G-T mismatched or "wobble" base pair, and one in which the thymine in this base pair is replaced by difluorotoluene (a thymine isostere) creating a G-F pair. Here, we show that the non-hydrogen-bonding G-F pair stacks relatively well into the helix and that the distortions caused by each non-Watson-Crick G-T or G-F base pair are quite localized to a three base pair site around the mismatch. A detailed structural analysis reveals that the absence of hydrogen bonding introduces more dynamic motion into the G-F pair relative to G-T and permits the G-F pair to exhibit stacking and conformational features characteristic of both a Watson-Crick base pair (on the guanine containing strand) and a wobble base pair (on the strand containing the difluorotoluene). We used these results to posit a rationale for recognition and repair of mismatch sites in DNA.     

Thermal behavior of a sol–gel system containing aniline and organic phosphonates

Samples of an organic–inorganic hybrid were prepared by solvolysis and polycondensation in formic acid of tetraethoxysilane and diethylbenzyl phosphonate, simultaneous with the oxidative polymerization of aniline. The thermal behavior of the samples in dynamic air atmosphere and non-isothermal conditions was determined by a coupled thermogravimetric/evolved gas analysis. Two significant thermal events were established: the elimination from the polymeric matrix of low mass molecules, respectively the thermooxidative degradation of the organic part of the matrix. The kinetic analysis was performed with the Flynn-Wall-Ozawa, Friedman and modified Non-Parametric-Kinetic methods. Only the last one allowed an objective analysis of the first process as a process of two simultaneous thermally induced phenomena with the kinetic functions of the type α^m(1 − α)ⁿ.     

Cation template assisted electrosynthesis of a highly π-conjugated polythiophene containing oligooxyethylene segments

A polythiophene precursor involving two bithiophene groups linked by an oligooxyethylene chain has been synthesized. Electropolymerizations performed in the presence of tetrabutylammonium, lithium, sodium and barium perchlorate show that the nature of the electrolyte cation strongly affects the polymerization process. The electrochemical and spectroelectrochemical properties of the resulting polymers show that the presence of barium cation in the electrosynthesis medium leads to a 300 mV decrease in the oxidation potential of the polymer, together with a significant red shift in the absorption maximum providing conclusive evidence for a metal template effect during electropolymerization.     

Molecular structure of compounds containing a 2,2′-bithienyl fragment (review)

The results of X-ray crystallographic investigations of compounds containing a 2,2-bithienyl fragment are summarized and analyzed. The structural characteristics of unsubstituted bithiophene, 5-monosubstituted, 5,5-, 3,3-, 4,4-, and 3,4-disubstituted, and more highly substituted bithiophenes and also the structure of -conjugated oligothiophene derivatives are considered.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–760, June, 2000.     

Synthesis of bis-β,β′-spiro-pyrrolidinyl-oxindoles,containing a rhodanine fragment

The synthesis of isatilidene derivatives of N-alkylrhodanines has been carried out with dipolarophiles and unstable azomethine ylides, generated in situ from sarcosine and paraformaldehyde. A series of chiral pyrrolidinyl-oxindoles spirofused in the β,β′-positions has been synthesized in the result of cycloaddition in high yield and diastereoselectivity.     

Synthesis and structure-activity relationships study of α-aminophosphonate derivatives containing a quinoline moiety

Two series of a-aminophosphonate derivatives containing a quinoline moiety have been designed and synthesized by introducing bioactive quinoline scaffold to a-aminophosphonate. The in vitro cytotoxic activities of target compounds were first investigated against two human cancer cell lines including Eca109 and Huh7 by MTT assay. Results revealed that most of target compounds exhibited moderate to high antitumor activities against the tested cancer cell lines and some demonstrated more potent inhibitory activities compared with Sunitinib. Among them, compounds 4b2 and 4b4 containing methylsubstituted aniline group were found to be more active than Sunitinib against both of two cancer cell lines, with IC50 in the range of 2.26 mmol/L–7.46 mmol/L.     

Synthesis,structure and reactivity of complexes containing a transition metal–bismuth bond

The transition metal chemistry of bismuth has attracted significant interest since the 1970s. The low cost and high abundance of bismuth(III) reagents, such as the trihalides, makes them ideal starting materials and the size of the bismuth centre allows three- and higher-coordinate complexes to be synthesised, in which the bismuth atom is linked to one or more transition metal fragments. The ability to vary these metal fragments gives access to a plethora of available structures, with cyclopentadienylcarbonyl, metal carbonyl and sandwich compounds of bismuth in existence. Significant recent study has focused on applications in catalysis, where bismuth species can act as cross-coupling agents in carbon–carbon, carbon–nitrogen and carbon–oxygen bond forming reactions. Another striking feature is the variation in bonding situations that can be observed when studying the organometallic chemistry of bismuth. For example, dative and covalent interactions have been reported, in addition to cases of dibismuth acting as a two-, four- or six-electron donating ligand. This review aims to demonstrate the multi-faceted nature of the transition metal chemistry of bismuth and provide a detailed coverage of this topic.     

Synthesis of novel β-amino ketones containing a p-aminobenzoic acid moiety and evaluation of their antidiabetic activities

The synthesis of two series of β-amino ketones containing a p-aminobenzoic acid moiety (TM-1 and TM-2) using a modified protocol of the Mannich reaction is reported. The molecular structures of a total of tweenty three new target compounds were characterized by 1H NMR, 13C NMR, ESI-MS and HR-MS. Subsequently, their antidiabetic activities were screened in vitro. The α-glucodase inhibition (α-GI) activity of compound 1e reached a remarkable level of 66.50%. The peroxisome proliferatoractivated receptor (PPAR) relative activation activities of six compounds are above 80%, and in particular 2i displays an unprecedentedly high PPAR of 130.91%. The structure-activity relationships of the compounds were established. 2i is also subject to further in-depth investigation.     

Ring opening of heterocycles containing a C–N double bond: a simple synthesis of imides promoted by acyl palladium species

A detailed study on the reactivity of various heterocycles, containing a C–N double bond, with acyl palladium species, generated in situ from allyl or benzyl halides and CO, has been performed. While the cyclic imine 2-methyl-1-pyrroline reacted with acyl-palladium intermediates to give a bicyclic β-lactam, other heterocycles containing a C–N double bond conjugated with a heteroatom (O or N), showed a ring-opening reaction leading to functionalized imides with high structural diversity. Such methodology represents a simple and direct way to prepare structurally complex imides. Moreover, a reaction mechanism, involving cationic intermediates, was also proposed.     

Neutron diffraction study of the HF adducts containing a hydrogen bond F-H?O

Single-crystal structures of HF adducts of acid salts CsH₂PO₃·HF, KH₂PO₄·HF, and CsH₂PO₄·HF were determined by neutron diffraction using the Laue method. In the crystals, HF molecules are connected to anions by means of new type of hydrogen bonds, F-H?O, which are significantly shorter (F?O distances 2.356-2.386(3) Å) than strong O-H?O or O-H?F hydrogen bonds. The H-F distances in the structures of these adducts, 1.020-1.027(5) Å, are compared with those in crystalline HF and hydrofluoride anions.     

Synthesis of new nanocopolymer containing β-lactams

Several new monocyclic β-lactam monomers bearing the NO₂ group 2a–g were synthesized via a [2 + 2] ketene–imine cycloaddition reaction (Staudinger reaction). Calculation of coupling constant of H-3 and H-4, and the X-ray crystallography of β-lactam 2e confirmed the cis stereochemistry of these β-lactams. Then aminophenyl β-lactams were synthesized by the reduction of NO₂ to NH₂ group in the presence of Raney Ni and hydrazine hydrate. Treatment of these aminophenyl β-lactams with acryloyl chloride and sodium bicarbonate (NaHCO₃), afforded the monomers bearing the NHCOCH=CH₂ group. These acrylated β-lactam monomers were dissolved in a warm mixture of butyl acrylate and styrene and then were converted to the corresponding polyacrylate nano β-lactams by emulsion polymerization in water. A unique feature of this methodology is the ability to incorporate water-insoluble compounds directly into the nanoparticle framework. Structures of the synthesized compounds were confirmed by physical and spectral analyses. Dynamic light scattering analysis and transmission electron microscopy of the final emulsions show that the nanoparticles were about 50–70 nm in diameter.     

Synthesis of a unique dimethyl thiazoline containing intermediate of novel peroxisome proliferator-activated receptors(PPAR)δ agonists

Peroxisome proliferator-activated receptor delta (PPARδ) is considered as a promising biological target for the development of new drugs to treat metabolic syndrome including hyperlipidemia. In this study, a simple and efficient method for the preparation of a unique dimethyl thiazoline containing intermediate (13) of new PPARδ agonists as GW501516 analogue is described. The intermediate 13 was readily obtained by coupling reaction of 4-(chloromethyl)-5,5-dimethyl-2-(4-(trifluoromethyl)phenyl)-4,5-dihydrothiazole (11) with 4-mercapto-2-methylphenol (12) in the presence of tetrabutylammonium hydrogensulfate (TBAHS) and Cs₂CO₃ in DMF at 80?°C for 1?h. This unique intermediate could be useful for the synthesis of various novel PPARδ agonists to understand the structural and biological significance of PPARδ.