Reaction of amino acid derivatives with C_(60)

Ammo acid derivatives react with C60 at 110-120℃to form adduct compounds.The products were isolated by column chromatography and were identified by FD-MS,UV-Vis,FT-IR and 13C NMR spectroscopies.     

Controlling the properties of poly(amino ester urethane)–poly(ethylene glycol)–poly(amino ester urethane) triblock copolymer pH/temperature-sensitive hydrogel

A series of triblock copolymers composed of poly(ethylene glycol) (PEG) and poly(β-amino ester urethane) (PAEU) was synthesized and characterized. Its aqueous solution can be used as a non-cytotoxic, biodegradable, and pH/temperature-sensitive hydrogel system. The copolymer solutions exhibited sol-to-gel and gel-to-sol transitions with increasing pH and temperature, respectively. The properties of this hydrogel system, such as its sol–gel transition diagram, mechanical properties, and degradation rate, can be controlled by modulating the PEG molecular weight, PAEU block length, copolymer concentration, or structure of the monomers. The presence of urethane groups and ionized tertiary amine groups in the copolymer solution at lightly acidic pH may lead to a strong interaction of the copolymer with formulated bioactive therapeutic agents, while the existence of the gel state under physiological conditions (37 °C, pH 7.4) may enable this copolymer hydrogel to be applicable as a drug/protein carrier.     

pH-responsive star-shaped functionalized poly(ethylene glycol)-b-poly(ε-caprolactone) with amino groups

Functional star-shaped 4-arm poly(ethylene glycol)-b-poly[(ε-caprolactone-co-γ-amino-ε-caprolactone)] (4-arm PEG-b-P(CL-co-ACL) was synthesized through ring-opening polymerization. The structure of the copolymer was confirmed by ¹H NMR, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). To further understand the copolymers, the difference of the conversion rate between ε-caprolactone (CL) and γ-(carbamic acid benzyl ester)-ε-caprolactone (CABCL) and the detailed deprotection condition were studied. The thermal property of the copolymer was analyzed by WAXR and differential scanning calorimetry (DSC), which demonstrated that the thermal property could be well adjusted. The pH-responsive behavior of the copolymers was studied in detail by dynamic light scattering (DLS), pH titration, and pyrene fluorescence methods, which indicated that it could form micelles and exhibit pH responsibility. Moreover, the copolymer was nontoxic and had good biocompatibility according to the results by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay.     

微量元素与阿尔茨海默病(9)

阿尔茨海默病(AD)是目前老年人最为关注的重要健康问题。中国55岁以上人群的AD患病率已超过2.0%,患病总人数在600万以上,中国已成为全球痴呆人数最多、速度增加最快的国家。至今人们对该病病因及其机制的了解仍然有限,亦无有效的药物可以阻止和治疗该病的发生和发展。该文在前人研究的基础上,全面总结并提出了该病病理的微量元素稳态障碍假设,详尽阐述了新学说的三个组成部分及四个方面的实践证据。     

A short synthesis of (S)-α-(diphenylmethyl)alkyl amines from amino acids

A range of (S)-α-(diphenylmethyl)alkyl amines were prepared from the corresponding (S)-α-amino acid ester hydrochlorides. These amines were derived by direct hydrogenation of their precursor oxazolidinones.     

Improved procedures for the synthesis of (S)-2-[N-(N′-benzylprolyl)amino]benzophenone (BPB) and Ni(II) complexes of Schiff's bases derived from BPB and amino acids

(S)-N-Benzylproline (BP) was obtained by the reaction of (S)-proline and benzylchloride in high chemical yield (89%). (S)-2-[N-(N′-Benzylprolyl)amino]benzophenone (BPB) was synthesized in amounts greater than 100 g by the SOCl₂ promoted condensation of BP with 2-aminobenzophenone (yield 82%). Ni(II) complexes of Schiff's bases derived from BPB and amino acids were prepared by an improved procedure involving the use of KOH as a base and MeOH as solvent (yield 90–91%).     

Preparation of (±)-α-alkylated amino acid derivatives via imidazoles

Photooxidatlon of N-methoxy-2,4-disubstituted imidazoles, readily available by way of a three component cyclization followed by O-alkylation, leads to stable acyl Imines which react with various organometallics to afford α,α-disubstituted amino acid bis-amides in good yields.     

N-(5-hydroxy-3′,4′-ethylenedioxyisoflavonyl-7-oxyacetyl)amino acids

For the purpose of seeking new biologically active compounds in the flavonoid series, a series of N-(5-hydroxy-3,4-ethylenedioxyisoflavonyl-7-oxyacetyl)amino acids was synthesized; their structure was confirmed by PMR spectral data.Taras Shevchenko Kiev University, Kiev 252033, Ukraine. Institute of Bioorganic Chemistry and Petrochemistry, Academy of Sciences of the Ukraine, Kiev 253660. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 482–486, April, 1998.     

Reactivity of thio (amino) derivatives of the ω-(4-hydroxyaryl)alkyl type in radical reactions

The enthalpies, activation energies, and rate constants of the reactions of thio (amino) alkylphenols of different structures were calculated and compared with those of the reactions of alkyl-substituted phenols, alkoxyl and alkyl radicals, hydroperoxides, and nitrogen dioxide, as well as the reactions of phenoxyl radicals with molecules of the substrate being oxidized. The calculation was performed by the intersecting parabolas method using O-H bond energy data for phenols. The correlation between the molecular structure of the thio (amino) alkylphenols and their reactivity in radical reactions is considered.     

Topological evolution of cerium(Ⅲ) molybdate microflake assemblies induced by amino acids

In this work, cerium(Ⅲ) molybdate microspheres configured as microflakes were synthesized in the presence of lysine via a hydrothermal process. We studied the role of lysine and other amino acids on the morphologic control of cerium(Ⅲ) molybdate crystals. First, with the increase of lysine, thinner microflakes and smaller microspheres are obtained. Moreover, a transformation in topology of cerium(Ⅲ) molybdate assemblies from three-dimensional(3D) into two-dimensional(2D) can be ascribed to controlled nucleation and growth of cerium(Ⅲ) molybdate induced by lysine. Second, amino acids with strong hydrophilic ‘‘R' groups tend to induce nucleation and result in spherical assemblies formed by nanoparticles or nanoflakes, while those with weaker hydrophilic ‘‘R' groups tend to induce growth and yield spherical assemblies of microflakes.     

An easy route to exotic 9-epimers of 9-amino-(9-deoxy) cinchona alkaloids with(8S,9R) and(8R,9S)-configurations through two inversions of configuration

Four exotic chiral organocatalysts, 9-amino-（9-deoxy） cinchona alkaloids with （8S, 9R） and （8R, 9S）- configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids.     

Rhodium(I) carbonyl complexes with α-diimine ligands containing amino or hydroxy substituents

-Diimines, RN:C(R)C(R):NR(LL) derived from glyoxal, GLL (R=H) abbreviated as GAA (R= R=4-dimethylaminophenyl) or GHA (R= R=4-hydroxyphenyl), and derived from biacetyl, BLL (R=Me) abbreviated as BDH (R=R= NH₂), BOH (R=NH₂, R=OH) react with carbonylrhodium(I) compounds to give different products depending on the imino substituents in the ligand and/or the solvent employed. The reaction of -diimines bearing amino groups, such as GAA or BDH with [RhCl(CO)₂]₂ in acetone yields binuclear [RhCl(CO)₂]₂(-LL) while in CH₂Cl₂ ionic [Rh- (CO)₂(LL)]⁺[RhCl₂(CO)₂]^– species are obtained. In acetone [RhCl(CO)₂]₂(-GAA) exists as an equilibrium mixture between two different neutral binuclear species; [Rh(CO)₂(BDH)]⁺ exists as a mixture of two species containing chelate or monodentate bonded diimine respectively. GAA or BDH react in situ with [RhCl(CO)(C₂H₄)]₂ in benzene to yield tetracoordinated monocarbonylated [RhCl(CO)(LL)] compounds. -Diimines (LL) bearing hydroxy groups, such as GHA or BOH react with [RhCl(CO)₂]₂ or [RhCl(CO)(C₂H₄)]₂ to give pentacoordinated dicarbonylated [RhCl(CO)₂(LL)] compounds.