Asymmetric synthesis of diarylmethylamines: preparation of selective opioid delta receptor ligands

Two different methods were used for the construction of optically active diarylmethylamines. Diastereoselective alkylation on an aldimine/oxazolidine 2a/2b derived from (R)/(S)-phenylglycinol or enantioselective reduction of 4-[η⁶-chromium tricarbonylbenzoyl] bromobenzene using chiral oxazoborolidine followed by amine introduction to furnish optically active diarylmethylamines.     

Synthesis of enol ethers from lactones using modified Julia olefination reagents: application to the preparation of tri- and tetrasubstituted exoglycals

A new route to substituted exoglycals from the corresponding lactones is described. The enol ethers synthesis via a modified Julia olefination of sugar-derived lactones is extended to substituted benzothiazolyl sulfones to furnish tri- and tetrasubstituted exoglycals.     

Highly selective molecularly imprinted overoxidized polypyrrole colloids: one-step preparation technique.

A convenient "one step" preparation process of molecularly imprinted overoxidized-polypyrrole (oPPy) colloids by chemical polymerization and their high uptake ability and enantioselectivity are described. Since an oxidizing agent gives a different standard redox potential and rate of polymerization, the property of the resulting oPPy colloid can be controlled by the kind and concentration of the oxidizing agent. At higher concentrations of (NH4)2S2O8 (0.3 M), the overoxidation of PPy colloid automatically occurred. The extraction of L-lactate as a dopant has created a shape-complementary cavity on the surface of the oPPy colloid through overoxidation following polymerization. The oPPy colloid exhibited an excellent selectivity not only on the alanine enantiomer but also on the difference in the side-chain size of amino acids. The uptake of oPPy colloid towards L-alanine over D-alanine was 11.3 micromol/g-colloid against 3.6 micromol/g. The molecularly imprinted cavity can also recognize the existences of the OH or CH3 substituents.     

Modified anthracites as selective sorbents for platinum metals

Methods of preliminary modification were used to obtain activated carbons with low ash content (0.2%), developed π-conjugated electronic system, large surface area, and wide pore size distribution, from exclusively microporous carbons to those of mesoporous type. The adsorption of compounds of platinum-group metals on activated anthracite from single-component (as regards the platinum metal: Pd, Pt, or Rh) and multicomponent (Pd, Pt) solutions containing compounds of concomitant metals was studied.     

Hydrothermal preparation of boehmite nanorods by selective adsorption of sulfate

A facile hydrothermal method was developed to synthesize boehmite nanorods with a length of 50-2000 nm, a diameter of 6-20 nm, and a preferential growth along [100] by treating the Al(OH)(3) gel in acidified sulfate solutions at 240 degrees C. Studies on the hydrothermal treatment of Al(OH)(3) gel in sulfate solutions showed that the morphology and the composition of the hydrothermal products were connected with the sulfate concentration and the pH of the hydrothermal solution. The aspect ratio of the boehmite nanorods increased to 300 as the initial H(2)SO(4) concentration increased to 0.043 mol x L(-1), whereas boehmite nanorods and (H(3)O)Al(3)(SO(4))(2)(OH)(6) cubic particles coexisted in the case of the initial H(2)SO(4) concentration > or = 0.054 mol x L (-1). Sole boehmite nanoflakes with a diameter of about 50 nm were formed under alkaline conditions (pH 10.5) despite the existence of the sulfate. The chemical and Raman analyses indicated that SO(4)(2-) in acidified solutions adsorbed on the boehmite surface via H-bonds. On the basis of the above results, the growth of boehmite along the [100] direction was attributed to the selective adsorption of SO(4) (2-) on the (010) and (001) planes of boehmite.     

左氧氟沙星选择性电极的制备及其性能研究

以左氧氟沙星与四苯硼酸根形成的缔合物为电活性物质,研制了一种左氧氟沙星PVC膜涂层玻璃电极,并对其响应性能进行了系统研究.实验表明,该电极的Nernst响应范围为5.0×10-3～2.0×10-5 moL/L,斜率为51.7 mV/pC,适用pH范围为3.0～4.5.该电极制作方法简单,响应迅速,重现性好,用于左氧氟沙星注射液和片剂的测定.     

Synthesis of Pterostilbene by Julia Olefination

A simple, E-stereoselective route for the synthesis of the biologically active compounds trans-pterostilbene and tetramethoxy stilbene from the readily available starting materials 3,5-dimethoxy benzyl alcohol and 4-hydroxy benzaldehyde was developed using Julia olefination as a key reaction.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]     

New insights into the selective and systematic preparation of arylgermanium hydrides

A series of novel arylgermanium hydrides Ar_nGeH_4–n (n = 1–3) and diaryl(chloro)germanium hydrides Ar₂Ge(Cl)H were synthesized and characterized. Systematic preparation and purification were achieved via the lithium chloride–triflic acid and the optimized Grignard route. Arylgermanium hydrides ArnGeH_4–n (Ar = 2,5-Me₂C₆H₃, n = 1–3) were characterized by ¹H and ⁷³Ge NMR spectroscopy and single crystal X-ray diffractometry.     

Efficient and controllably selective preparation of esters using uronium-based coupling agents

Carboxylic acid esters can be prepared in excellent yields at room temperature from an acid and either a phenol or an aliphatic alcohol using the peptide coupling reagents, TBTU, TATU, or COMU, in the presence of organic bases. Reactions using TBTU and TATU are faster but do not occur with tertiary alcohols. Selectivity between reaction with primary or secondary alcohols in diols and polyols can be achieved with choice of base and coupling agent.     

盐酸甲胺三氧铬的制备及其α,β-不饱和醇的选择性氧化

本文报道盐酸甲胺三氧铬(3)的制备方法,并在DMF中作了一些醇的氧化试验,试验结果表:3其有很高的氧化选择性,它能顺利地将多种α,β- 不饱和醇氧化成相应的醛或酮;而在相同条件下,不氧化饱和醇, 并且在一定条件下可以氧化分子内的苄醇羟基而不氧化同一分子中的酚羟基和饱和醇羟基。3在DMF中使用时, 没有明显的酸性,可以用于氧化对酸敏感的化合物,而且它制备简单,使用条件温和,是一种优良的高选择性氧化剂。     

Heteroligand and heteronuclear clamshell-type phthalocyanines: selective preparation, spectral properties, and synthetic application

A direct synthetic method to produce heteronuclear and heteroligand clamshell-type binuclear phthalocyanines via a nucleophilic coupling reaction between A₃B-type monophthalocyanines is developed with the target compounds demonstrating the possibility to form sandwich-type heterocomplexes for the first time.     

氧化铬层柱苯膦酸锆的合成与选择氧化性能

采用乙胺预胶体化方法合成了一系列氧化铬层柱苯膦酸锆和氧化铬层柱磷酸锆催化剂,其铬含量达到22.5%-36.5%,比表面为316-462m^2/g,中孔孔容占总孔容的70%以上,孔径集中在2nm左右。氧化铬层柱苯膦酸锆的热稳定性较高。以30%H~2O~2为氧化剂时,这类催化剂对苯、甲苯、乙苯、环己烷、环己烯、正庚烷和正丁醇等有机化合物具有比CrAPO-11和CrMCM-41更高的选择氧化活性。     

A simple method for the preparation and selective functionalization of 4,5-diaminopyrazoles

A simple procedure for the synthesis and further functionalization of 4,5-diaminopyrazoles using mild conditions is reported herein. The desired products were obtained in good yield, and the structures have been confirmed by X-ray crystallography.     

A phosphorimidate rearrangement for the facile and selective preparation of allylic amines

Allylic phosphorimidates, readily prepared from the combination of an allylic alcohol, an azide, and a chlorophosphite, undergo [3,3]-rearrangement under thermal conditions to provide single isomers of allylic phosphoramidates. This new rearrangement is tolerant of a range of substitution patterns on the reactants. Treatment of the products of the rearrangement with ethanethiolate followed by acid produces a protected allylic amine. This strategy thus provides an attractive and versatile procedure for the preparation of key synthetic intermediates, allylic amines.     

The selective preparation of an aluminum oxide and its isomeric C-H-activated hydroxide

An aluminum oxide [LAlO]2 (1) has been prepared by the oxidative addition of aluminum(I) monomer LAl (L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3) with molecular oxygen. The short Al-O bonds in Al2(mu-O)2 result in short Al...Al contacts and subsequent steric crowding of the Ar substituents from the two oriented L. 1 hydrolyzes to form [LAl(OH)]2(mu-O) (2). A C-H-activated aluminum hydroxide 4, an isomer of 1, however, is obtained by hydrolysis of the bulky aluminum amide 3 rather than by a conversion by high temperature treatment of 1. This indicates selective preparation of isomers 1 and 4.     

咪草烟分子印迹聚合物的制备及其选择性吸附性能的研究

以丙烯酸为聚合单体,TMPTA为交联剂,AIBN为引发剂,咪草烟为模板分子,采用在低温光聚合的方法,制备了对咪草烟分子具有选择性识别能力的分子印迹聚合物．通过IR和HPLC表征,咪草烟分子印迹聚合物对咪草烟分子具有良好的识别作用．     

Modified boron nitride as an efficient synergist to flame retardant natural rubber: preparation and properties

A new flame retardant system with organic modified boron nitride (m‐BN) and intumescent flame retardant (IFR) was used in this paper, and the synergistic flame retardancy of m‐BN and IFR on natural rubber (NR) was studied. NR/IFR/m‐BN composites were characterized by X‐ray photoelectron spectroscopy(XPS), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis, UL‐94, limiting oxygen index (LOI), tensile testing, cone calorimeter testing, and thermal conductivity testing. When 4 wt% m‐BN was added, the flame retardancy and mechanical properties of the composites were improved. The LOI value of NR/IFR/4 phr m‐BN reached 26.8%, and suppressed fire spread in a UL‐94 test. Compared with pure NR, the peak heat release rate (pHRR) was reduced by 52.2%, the total heat release (THR) was reduced by 27.6%, and CO yields were reduced by 51.4%. As a key aspect of fire safety, the ignition time is effectively delayed to 23 seconds due to the increased thermal conductivity of NR/IFR/m‐BN. Since the synergistic effect of m‐BN effectively improves the flame retardancy of NR, it provides a feasible method for improving the fire safety of polymers.