Ionic-tag-assisted synthesis of nucleoside triphosphates

We describe an ionic-tag-assisted synthesis of nucleoside triphosphates that combines the advantage of one-pot triphosphate formation and liquid-phase extraction.     

Synthesis and Characterization of Rare Earth Orthovanadate (RVO4; R = La, Ce, Nd, Sm, Eu & Gd) Nanorods/Nanocrystals/Nanospindles by a Facile Sonochemical Method and Their Catalytic Properties

We report herein on an efficient sonochemical method for the synthesis of rare earth orthovanadate nanorods/nanoparticles/nanospindles, (general formula RVO₄; R = La, Ce, Nd, Sm, Eu and Gd). TGA, XRD, FTIR, Raman, UV–Vis, and TEM studies are employed for their characterization and for understanding their morphologies. In order to vary the textural properties of the rare earth vanadates, two surfactants, polyethylene glycol (PEG) and amphiphilic triblock copolymer Pluronic P123, are chosen in the preparation. While the sonochemical synthesis in the presence of PEG results in the formation of nearly spherical nanoparticles of LaVO₄, CeVO₄, SmVO₄ and EuVO₄, the same technique yields nanorods and nanospindles of NdVO₄ and GdVO₄, respectively. When P123 is used as the surfactant, the morphologies of RVO₄ are strikingly different, and in most cases nanorods and nanospindles are formed. The photocatalytic activities of the rare earth orthovanadate have been evaluated by studying the degradation of methylene blue, and CeVO₄ seems to be the best catalyst in the heterogeneous photolysis. The electrocatalytic activity of the vanadates has been examined by studying the hydrogen evolution reaction using a linear sweep voltammogram technique in 1 M of a H₂SO₄ solution. GdVO₄ seems to be the best electrocatalyst. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

An efficient biomimetic Fe-catalyzed epoxidation of olefins using hydrogen peroxide

A new, environmentally benign and practical epoxidation method was developed using inexpensive and efficient Fe catalysts. FeCl3.6H2O in combination with commercially available pyridine-2,6-dicarboxylic acid and amines showed excellent reactivity and selectivity towards aromatic olefins and moderate reactivity towards 1,3-cyclooctadiene utilizing H2O2 as the terminal oxidant.     

Role of the conformational changes brought in the arms of the 1,3-di-capped conjugate of calix[4]arene (L) in turning on the fluorescence of L by Hg2+

A new 1,3-di-capped calix[4]arene conjugate of salicylidene (L) has been synthesized, characterized and the structure has been established by single crystal XRD. L shows selectivity towards Hg(2+) in ethanol by turn-on fluorescence among the biologically important metal ions studied. The species of recognition has been modeled by DFT computational calculations to result in conformational changes in the arms that support the turn-on fluorescence behaviour.     

Anti-cancer activity of novel dibenzo[b,f]azepine tethered isoxazoline derivatives

Background  

Nef is an HIV-1 accessory protein essential for viral replication and AIDS progression. Nef interacts with a multitude of host cell signaling partners, including members of the Src kinase family. Nef preferentially activates Hck, a Src-family kinase (SFK) strongly expressed in macrophages and other HIV target cells, by binding to its regulatory SH3 domain. Recently, we identified a series of kinase inhibitors that preferentially inhibit Hck in the presence of Nef. These compounds also block Nef-dependent HIV replication, validating the Nef-SFK signaling pathway as an antiretroviral drug target. Our findings also suggested that by binding to the Hck SH3 domain, Nef indirectly affects the conformation of the kinase active site to favor inhibitor association.     

A novel catalyst-free,eco-friendly,on water protocol for the synthesis of 2,3-dihydro-1H-perimidines

The first greenest methodology for the synthesis of 2,3-dihydro-1H-perimidines on water is described. 1,8-Diamino naphthalene was reacted with different types of aldehydes at room temperature to furnish the product in moderate to excellent yields in 30 min. A multi-gram scale reaction is also performed to ensure the scalability of the reaction.     

An efficient room temperature preparation of bromo difluorovinylzinc reagent (CF2CBrZnCl) and a high yield one-pot synthesis of α-bromo-β,β-difluorostyrenes

A high yield room temperature preparation of the1-bromo-2,2-difluorovinylzinc reagent [CF₂CBrZnCl] (>89%) was achieved via insitu metallation of CF₃CH₂Br or CF₂CHBr with LDA in presence of ZnCl₂. Palladium catalyzed cross-coupling of this zinc reagent with aryl iodides provides α-bromo-β,β-trifluorostyrenes (ArCBrCF₂) in 64-86% isolated yields, in an essentially ‘one-pot’ procedure.     

Synthesis and characterization of new azobenzenesulfonic acids doped conducting polyaniline

New azobenzene sulfonic acid dopants were synthesized by diazotized coupling reaction of sulphanilic acid diazonium salt with commercially available raw materials such as phenol, m-cresol and 4-phenylphenol. The structures of the dopants are confirmed by NMR and FT-IR. Polyaniline emeraldine base was doped by these new azobenzenesulfonic acid dopants in two different solvent medium such as methanol and N-methylpyrrolidinone to produce green emeraldine salt. The doping process was confirmed by FT-IR and UV-vis spectroscopy. The effect of composition of dopant on the conductivity of the polyaniline was investigated and the results suggest that the conductivity increases with the increase in the dopant concentration and attained maxima for more than 38% in the feed. The conductivity measurements reveal that all the dopants equally effective in producing in high conductivity in the range of 0.02 S/cm and the conductivity of the doped samples are insignificant to the structural difference in the dopant. WXRD and SEM analysis indicate that the doped samples are highly amorphous and porous in nature. The thermal analysis by TGA indicate that all the doped materials were highly stable up to 300 °C for high temperature applications.     

Room temperature preparation of α-chloro-β,β-difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes

α-Chloro-β,β-difluorovinylzinc reagent [CF₂CClZnCl] was generated in 91% yield by the metallation of a THF solution of commercially available HCFC-133a (CF₃CH₂Cl) and zinc chloride at 15-20 °C using LDA as base. The corresponding reaction with Halothane™ (CF₃CHClBr) produced a poor yield of CF₂CClZnCl. The palladium catalyzed coupling reaction of the CF₂CClZnCl with aryl iodides under mild reaction conditions produced α-chloro-β,β-difluorostyrenes in 64-90% isolated yields. The stability of the intermediate CF₂CClLi and the nature of the zinc reagents are discussed.     

Targeted glycosyl donor delivery for site-selective glycosylation

[reaction: see text]n-Pentenyl ortho esters (NPOEs) and n-pentenyl glycosides (NPGs) are interconvertible glycosyl donors which are activated by reaction with halonium ions. In a series of cyclic syn-1,3-diols, NPOEs have been found to specifically glycosylate the equatorial-OH while the NPG glycosylates predominantly, but not exclusively, the axial-OH. When the cyclic diol acceptor is presented with equivalent amounts of an NPOE and an NPG in a three-component-reaction, a single, double-glycosylation product is obtained, which conforms to the foregoing preferences, presenting evidence for site-selective glycosylation.