A simplified method for the preparation of α-32P-labeled deoxyribonucleoside triphosphates

A method for preparing α-³²P-labeled deoxyribonucleoside triphosphates ([α-³²P]dNTP)^* is described. By comparing the labeling procedure to that ofWalseth et al.^1,2 the reaction of Nuclease P₁ is saved in our experiments and only three steps are needed for a routine preparation, without decreasing the yield of [α-³²P]dNTP which is over 92% based on³²Pi. In this paper [α-³²P]dATP is taken as an example to deseribe the labeling procedure, the suitability of our method has been discussed.     

A facile preparation of (±)-β-hydroxy nitriles and their enzymatic resolution with lipases

A simple and efficient method for the preparation of racemic 4-aryloxy-3-hydroxybutanenitriles is described. Lipase mediated kinetic resolution in organic media was then utilised to effect enantioseparation. Lipases from different sources were screened in the resolution reaction using a number of organic solvents. Enantiomeric excesses of up to 99% were obtained by employing lipase from Pseudomonas cepacia in di-iso-propyl ether medium.     

A new method for the preparation of fluoro-λ-sulfanenitriles: reaction of sulfimides with Selectfluor™

Several diaryl(fluoro)-λ⁶-sulfanenitriles 3 were synthesized by the reaction of S,S-diarylsulfimides 1 with Selectfluor™. This reaction also allows the first preparation of heterocyclic fluoro-λ⁶-sulfanenitrile, 5-fluoro-10,10-dioxo-5,10-dihydro-5λ⁶,10λ⁶-thianthren-5-nitrile (5) and its molecular structure was determined by X-ray crystallographic analysis.     

A highly selective method for the synthesis of(E)-α-methyl-α,β-unsaturated aldehydes

Anhydrous acidic treatment of E,Z mixtures of α-methyl-α,β-unsaturated imines followed by hydrolysis gives the corresponding aldehydes with ≥ 100:1 E:Z ratios.     

Reaction of the dimethoxyaminyl radical with tertiary nitrosoalkanes as a method for the preparation of N-alkyl-N′-methoxydiazene N-oxides

The reaction of the dimethoxyaminyl radical with functionally substituted nitrosoalkanes (2) in a 2:1 ratio at 20°C gives the corresponding N-alkyl-N-methoxydiazene N-oxides (3) as a single isomer in preparative yields.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2443–2445, October, 1992.     

A general method for the preparation of N-heterocyclic carbene–silver(I) complexes in water

A new synthetic method leading to N-heterocyclic carbene–silver(I) complexes [(R₂-NHC)₂Ag]⁺ [AgX₂]^? is developed by using benzimidazolium compounds, NaOH (as a base), silver salts and water (as the reaction medium). Single-crystal X-ray structure revealed that compound 1 comprises a linear [Ag-(Et₂-Bimy)₂]⁺ cation and a linear [AgBr₂]^? anion. These two ions are linked through an Ag^I–Ag^I association and staggered at an angle of 90.3°.     

A new concise stereoselective method for the preparation of a β-hydroxyfurfurylamine derivative and synthesis of 1-deoxyazasugar isomers

A new method to prepare a chiral building block, a β-hydroxyfurfurylamine derivative, is achieved and 1-deoxyazasugar isomers are synthesized.     

Reactor production of 32P for medical applications: an assessment of 32S(n,p)32P and 31P(n,γ)32P methods

The article describes a comparative study carried out on the reactor production of ³²P by two different processes, namely, ³²S(n,p)³²P and ³¹P(n,γ)³²P with a view to determine the merits and bottlenecks of each method and assess the usefulness of ³²P obtained from each of the processes. In a typical batch, 250 g of elemental sulfur when irradiated at a fast neutron flux of ~8 × 10¹¹ n cm^?2 s^?1 for 60 days, after chemical processing provided about 150 GBq(4.05Ci) of ³²P having specific activity of 200TBq(5500Ci)/mmole. On the other hand, irradiation of 0.35 g of red phosphorus at a fast neutron flux of ~7.5 × 10¹³ n cm^?2 s^?1 for a period of 60 days gave 75 GBq(2.02Ci) of ³²P of specific activity 7 GBq(190mCi)/mol^-1. While the specific activity of ³²P obtained from ³²S(n,p)³²P is superior to that obtained from the ^3lP(n,γ)³²P process, the requirement of elaborate target processing steps involving distillation and purification emerged as a deterrent that limits its widespread adaptability. Both the production routes offer ³²P of acceptable quality amenable for medical applications although their specific activity differs.     

A novel polycondensation method for the synthesis of a two-faced β-1,4-glucan

Abstract  

The stereospecific synthesis of a chitosan derivative repeating 2-azido-3,6-di-O-benzyl-2-deoxy-β-d-glucopyranosyl-(1 → 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-d-glucopyranose, which has two distinguishing faces, was achieved by polycondensation of the sole starting disaccharide, trichloroacetimidoyl 2-azido-3,6-di-O-benzyl-2-deoxy-β-d-glucopyranosyl-(1 → 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-d-glucopyranoside in a short and efficient way.     

Gelation with N-lauroyl-L-glutamic-α,γ-dibutylamide for liquid scintillation counting of low specific activities of35S and32P

A gelling agent, N-lauroyl-L-glutamic-,-dibutylamide, was applied for liquid scintillation counting of inorganic³²P and³⁵S. The gel with toluene cocktail is transparent and rigid for a long time. Several grams of ammonium magnesium phosphate or barium sulfate can easily be measured without complicating procedures.     

A mild oxidative method for the preparation of γ-hydroxy-α-nitroolefins from α,β-epoxyketoximes using IBX

An efficient method for the preparation of γ-hydroxy-α-nitroolefins from α,β-epoxyketoximes has been developed using IBX. The reaction occurs at room temperature without the formation of over-oxidation products and also has an easy work-up procedure.     

Enantioselective synthesis of A key A-ring intermediate for the preparation of 1α,25-dihydroxyvitamin D(3)

A novel approach to the key A-ring α, β-unsaturated aldehyde 1, an important intermediate for the preparation of 1α,25-dihydroxyvitamin D(3), has been developed. The strategy started from the inexpensive starting material (R)-carvone with an ene reaction serving as the key step toward the potential synthesis of vitamin D(3) analogues bearing the modification at the C-2 position.     

A general method for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations. Part 1. Application of the MαNP acid method to acetylene alcohols

A method using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid 1 (MαNP acid) has been applied to acetylene alcohols 4–14 to determine their absolute configurations by ¹H NMR anisotropy and/or X-ray crystallography. Diastereomeric MαNP esters prepared from racemic acetylene alcohols and (S)-(+)-MαNP acid 1 were easily separable by HPLC on silica gel. From the ¹H NMR anisotropy Δδ data of separated diastereomeric MαNP esters {Δδ = δ (R,X) − δ(S,X) = δ(2nd fr.) − δ(1st fr.)}, the absolute configurations of the first eluted esters were determined. This MαNP acid method has been successfully applied to various acetylene alcohols 4–12 and 14. In the case of MαNP esters 21b, 24a, and 26a, their absolute configurations were unambiguously determined by X-ray crystallography, which confirmed the absolute configuration assignments performed by ¹H NMR anisotropy. These acetylene alcohol MαNP esters can serve as key intermediates for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations as described in Part 2 of this series.     

Silane-based poly(ethylene glycol) as a primer for surface modification of nonhydrolytically synthesized nanoparticles using the Stöber method

This paper describes the use of methoxy-poly(ethylene glycol) silane (MPEG-sil) as a linker molecule for the synthesis of silica-coated nanoparticles by the St?ber method. While short alkane chain-based siloxanes including (acryloxypropyl)trimethoxysilane and 3-methacryloxypropyl-trimethoxysilane are popular molecules used in surface modification, they are not efficient for the silica coating of nanoparticles synthesized from organic solvents containing long carbon chain carboxylic acids or amines as capping agents. Here, we report the utilization of MPEG-sil to bridge this gap. Our approach is based on a two-phase system, in which ligand exchange takes place in a hydrophobic environment and the surface modification with silica is conducted in an ethanol-water mixture. Our results show that this two-phased approach was effective to coat monodisperse Fe2O3 nanoparticles capped with oleic acid and Ag nanoparticles capped with oleylamine with uniform SiO2 shells. The process was also demonstrated for double-shell nanostructures to produce SiO2-coated Pt@Fe2O3 core-shell nanoparticles. The results described in this work represent a new approach for the surface modification with silica coating of monodisperse nanoparticles synthesized from nonhydrolytic solutions and can potentially have a broad ramification in the development of water-dispersible nanoparticles for biological applications.     

Structural characterization of a high affinity mononuclear site in the copper(II)-α-synuclein complex

Human α-Synuclein (aS), a 140 amino acid protein, is the main constituent of Lewy bodies, the cytoplasmatic deposits found in the brains of Parkinson's disease patients, where it is present in an aggregated, fibrillar form. Recent studies have shown that aS is a metal binding protein. Moreover, heavy metal ions, in particular divalent copper, accelerate the aggregation process of the protein. In this work, we investigated the high affinity binding mode of truncated aS (1-99) (aS99) with Cu(II), in a stoichiometric ratio, to elucidate the residues involved in the binding site and the role of copper ions in the protein oligomerization. We used Electron Paramagnetic Resonance spectroscopy on the Cu(II)-aS99 complex at pH 6.5, performing both multifrequency continuous wave experiments and pulsed experiments at X-band. The comparison of 9.5 and 95 GHz data showed that at this pH only one binding mode is present. To identify the nature of the ligands, we performed Electron Spin Echo Envelope Modulation, Hyperfine Sublevel Correlation Spectroscopy, and pulsed Davies Electron-Nuclear Double Resonance (Davies-ENDOR) experiments. We determined that the EPR parameters are typical of a type-II copper complex, in a slightly distorted square planar geometry. Combining the results from the different pulsed techniques, we obtained that the equatorial coordination is {N(Im), N(-), H(2)O, O}, where N(im) is the imino nitrogen of His50, N(-) a deprotonated amido backbone nitrogen that we attribute to His50, H(2)O an exchangeable water molecule, and O an unidentified oxygen ligand. Moreover, we propose that the free amino terminus (Met1) participates in the complex as an axial ligand. The MXAN analysis of the XAS k-edge absorption data allowed us to independently validate the structural features proposed on the basis of the magnetic parameters of the Cu(II)-aS99 complex and then to further refine the quality of the proposed structural model.     

A convenient,highly-efficient method for preparation of hydroxyl-terminated isotactic poly(propylene) and functional di-block copolymer

Both terminated functional isotactic polypropylene （iPP） and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hydroxyl-terminated isotactic polypropylene （iPP-t-OH） and functional di-block copolymer containing the iPP segment through a combination of coordination polymerization and coupling reaction. The coordination polymerization was catalyzed by TiCI4/MgCI2/AIEt3 catalyst system using ZnEt2 as chain transfer agent. Further, the Zn-terminated iPP was oxidized and subsequently hydrolyzed to provide iPP-t-OH. Soxhlet extraction and 13C NMR were used to calculate the isotacticity of iPP-t-OH. The degree of polymerization and the number of hydroxyl groups at the chain end of iPP-t-OH were measured by GPC and 1H NMR. Despite the high molecular weight and heterogeneous reaction, iPP-t-OH is effectively linked with PEG-t-NCO to produce di-block copolymers. DSC analysis of the di-block copolymer shows an obvious decrease in Tm and To, which indicated that PEG was successfully linked to the terminal end of iPP.     

A new efficient method for the preparation of intermediate aromatic ketones by Friedel–Crafts acylation

Research on Chemical Intermediates - As the most important method to prepare pharmaceutical and chemical intermediate aromatic ketones, Friedel–Crafts (F–C) acylation is used to seek a...     

Non-aqueous approach to the preparation of reduced graphene oxide/α-Ni(OH)2 hybrid composites and their high capacitance behavior

Reduced graphene oxide/α-Ni(OH)(2) composites present high electrochemical properties, with specific capacitance of 1215 F g(-1) at 5 mV s(-1) scan rate, since graphene as conductive matrix provides electronic conduction pathway.