A novel method for the formylation of Grignard reagent

A facile and efficient method for the formylation of Grignard reagent was reported, and a new approach for the preparation of aldehydes from Grignard reagent and benzimida-zolium salts was provided.     

Utilization of bromination reactions for the determination of carbamazepine using bromate–bromide mixture as a green brominating agent

One titrimetric and two spectrophotometric procedures have been developed for the assay of carbamazepine (CBZ) in bulk drug, formulations and spiked human urine. The methods are based on the bromination of CBZ by the bromine generated in situ by the action of the acid on the bromate–bromide mixture. The twin advantages of avoiding liquid bromine and analysis in a cost-effective manner are realized. In titrimetry, the drug was treated with a known excess of bromate–bromide mixture in hydrochloric acid medium followed by the determination of unreacted bromine iodometrically. Spectrophotometry involves the addition of a measured excess of bromate–bromide reagent in acid medium to CBZ, and after the reaction is ensured to be complete, the residual bromine was determined by reacting with a fixed amount of either methyl orange and measuring the absorbance at 510 nm (method A) or indigo carmine and measuring the absorbance at 610 nm (method B). Titrimetric procedure is applicable over the range of 1.00–7.50 mg CBZ, and the calculations are based on a 1:1 reaction stoichiometry (CBZ:KBrO₃). In spectrophotometric methods, Beer’s law is valid within concentration ranges of 0.25–1.50 and 0.50–6.00 μg ml⁻¹ CBZ for methods A and B, respectively. The proposed methods were successfully applied to the determination of CBZ in tablets and syrup, in addition to spiked human urine by the spectrophotometric methods, with mean recoveries of 95.50–104.0% and the results were statistically compared with those of an official method by applying Student’s t-test and F-test.     

Thiazolylblue tetrazolium bromide — a new spectrophotometric reagent for determination of manganese

A method has been developed for the micro-determination of Mn(VII) by the selective extraction of the MnO₄ ^– anion with thiazolylblue tetrazolium bromide from acidic medium. The molar absorptivity of the complex is 1 × 10⁴lmol^–1cm^–1 at 250 nm and the system obeys Beer's law in the range 0.1–1.75 gml^–1 Mn(VII). The composition and stability of the complex are discussed. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: extraction constantK _ex = 3.16 × 10⁴, distribution constantK _D = 21.85 and association constant =1.45 × 10³. Manganese(VII) was determined in soils and plants. The determination was carried out without preliminary separation of manganese.     

Mild synthesis of N’-aryl-N,N-dimethylformamidinium chloride by Vilsmeier-Haack reagent

Formamidine derivatives could be used as the building blocks for substituted heterocyclic compounds with various biological activities.N’-Aryl-N,N-dimethylformamidinium chlorides have been synthesized in high yields by reaction of aromatic primary amines with Vilsmeier-Haack reagent at room temperature.The structures of all the new compounds were identified by ESI-MS,IR and NMR spectra.The steric structures of some of these compounds were clarified by X-ray single crystal analysis.     

A new version of the conversion of plant polyprenols into (±)-terpenols of the dolichol series

A two-step method for the chemoselective reduction of the trisubstituted double bond of an α-isoprene unit in plant polyprenols was developed for the preparation of racemic terpenols of the dolichol series of mammals. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1491–1492, August, 2000.     

A facile approach for the synthesis of novel xanthene derivatives with Vilsmeier–Haack reagent

Chemistry of Heterocyclic Compounds - A series of new derivatives of formylxanthenes have been synthesized via the reaction of substituted 1,3-benzoxazines with Vilsmeier–Haack reagent. It...     

β-Trimethylsilylethanesulfonyl chloride (SES-Cl): A new reagent for protection of amines

The title compound, easily prepared in two steps from vinyltrimethylsilane, is a useful reagent for the protection of primary and secondary amines as their sulfonamides, which are cleaved by fluoride ion.     

Dehydration of α-silylalcohols in the reductive conversion of esters and ketones into alkenes

The conversion of esters and ketones into easily dehydrated α-silylated alcohols, and protodesilylation of the resultant vinylsilanes, gives alkenes under relatively mild acidic conditions.     

The conversion of nickel-bound CO into an acetyl thioester: organometallic chemistry relevant to the acetyl coenzyme A synthase active site

When three become one: Within one nickel-based model system, the three reactants CO, MeI, and PhSH have been assembled to yield an acetyl thioester. The reactivity is of relevance for the functioning of the acetyl coenzyme?A synthase active site and provides insights into possible binding sequences.     

Bromodimethylsulfonium bromide (BDMS): a useful reagent for conversion of aldoximes and primary amides to nitriles

An operationally simple and high yielding procedure has been developed for the preparation of nitriles from aldoximes and primary amides using bromodimethylsulfonium bromide (BDMS) as a novel and efficient reagent in the absence of any added base or catalyst. The optimal protocol is applicable to access a wide range of cyano compounds including aromatic, heterocyclic, and aliphatic species. The conversion of aldoximes to nitriles takes place at room temperature in acetonitrile, whereas acetonitrile at reflux temperature is required for rapid conversion in the case of primary amides.     

Bromodimethylsulfonium bromide (BDMS) in ionic liquid: a mild and efficient catalyst for Beckmann rearrangement

Bromodimethylsulfonium bromide (BDMS)-catalyzed Beckmann rearrangement of a variety of ketoximes has been carried out in the imidazolium-based ionic liquid [bmim]PF₆ under mild conditions without using any additional cocatalyst or solvent to afford excellent conversion and selectivity. The ionic liquid is recovered and reused for up to three runs without any loss of efficiency.     

Bromodimethylsulfonium bromide (BDMS)-catalyzed multicomponent synthesis of 3-aminoalkylated indoles

Bromodimethylsulfonium bromide (BDMS)-catalyzed three-component coupling reaction between indoles, aldehydes, and N-alkylanilines is reported to access substituted 3-aminoalkylated indoles at room temperature in high yields (82-96%) within 1.5-3.5 h. The salient features of this protocol are the simplicity of the procedure, the ready accessibility of the catalyst, its cost effectiveness, and higher yields in relatively short reaction times.     

9,10-二(苯亚甲基-硫亚甲基)蒽的合成及其对Cu2+的识别

荧光分子开关和分子识别是超分子化学的重要组成部分。蒽环作为一个优良的荧光基团被广泛应用于分子开关的设计及分子识别中。Resorci-narenes母体衍生物的合成研究中采用蒽环作为荧光基团已被报道多次[1-4],Luigi Fabbrizzi合成的多氨基蒽衍生物[5]对Zn2 具有良好的PET效应。蒽系荧光分子在分子逻辑门系统中日益受到了研究者的重视,de Silva等在研究中发现一蒽环化合物[6]在Mg2 作用存在OR逻辑行为。在后续研究中发现两类蒽环化合物在一定条件下分别存在AND[7]和NOR[8]逻辑行为。在分子识别的研究中,Shin-ichi Sasaki合成的含穴状…     

One-step biomimetic conversion of a furanoheliangolide into an eremantholide using Stryker’s reagent

The conversion of a furanoheliangolide structure (15-deoxygoyazensolide) into an eremantholide one (eremantholide C) was achieved by tandem hydride conjugate addition–intramolecular carbanion addition using Stryker’s reagent.     

Vilsmeier-Haack reagent: An efficient reagent for the transformation of substituted 1,3-naphthoxazines into xanthene-type dyes

Derivatives of 1,3-naphthoxazines containing from five to seven-membered spiro ring – under Vilsmeier–Haack reaction conditions are rearranged into novel xanthene-type compounds. All synthesized aminochromene derivatives fluoresce in organic solvents with extra large Stokes shifts (100–133?nm). It was found that compounds containing five-membered annulated aliphatic rings in methanol solution have the best spectral characteristics. These compounds have moderate quantum yields of 28.36–28.94%, and extra large Stokes shifts 106 and 115?nm.     

Phase Behavior and Vapor Pressures of the Pyrene + 9,10-Dibromoanthracene System

The present work concerns the thermochemical and vapor pressure behavior of the pyrene + 9,10-dibromoanthracene system. The phase diagram of the system has been studied using the thaw melt method and the results show the formation of non-eutectic multiphase mixtures. The temperatures of crystallization, and enthalpies of fusion and crystallization of the system were determined by differential scanning calorimetry. The system behavior can be divided into 5 regions. The X-ray diffraction results also indicated the existence of multiple phase characteristics. The solid-vapor equilibrium studies showed that for mixtures with high mole fractions of pyrene, two different preferred states exist that determine the vapor pressure. For those mixtures with moderate and low mole fractions of pyrene, only one preferred state exists that determines vapor pressure behavior. It was also demonstrated that the vapor pressure of the mixtures is independent of the mixture preparation technique.     

Piezochromic luminescence and aggregation induced emission of 9,10- bis[2-(2-alkoxynaphthalen-1-yl)vinyl]anthracene derivatives

Four derivatives of 9,10-bis[2-(2-alkoxynaphthalen-1-yl)vinyl]anthracene (BNAs) were designed, successfully synthesized and characterized by spectrofluorometer, powder wide-angle X-ray diffraction (PXRD) and differential scanning calorimetry experiments (DSC), etc. It was found that these compounds exhibited aggregation-induced emission phenomenon. Moreover, these target compounds displayed reversible color change from yellow to orange upon pressing and annealing process. Interestingly, all of BNAs obviously presented red-shifted piezofluorochromic (PFC) properties and behaved mainly length dependence of alkoxy group, in which, BNA displayed the largest PFC spectral shift (Δl_PFC=26 nm). The PXRD profiles demonstrated the transformation from crystalline to amorphous state upon grinding, and the mechanism of PFC behaviors was proposed. Thus, changing the length of alkoxyl chain could be an alternative way to tune their PFC behaviors.