Search

A One pot four-component domino reactions were developed for the synthesis of 5-methyl-4-(2-(3-methyl-4-nitroisoxazol-5-yl)-1-arylethyl)-1H-pyrazol-3-ols derivatives in excellent yield from hydrazine hydrate (1), ethyl acetoacetate (2), aldehyde (3) and 3,5-dimethyl-4-nitro-isoxazole (4) using 10 mol% of piperidine. This method is simple, efficient and multiple bonds were generated (two C−C, one C−N, one O−H and one C=N) in a single step. These novel 5-methyl-4-(2-(3-methyl-4-nitroisoxazol-5-yl)-1-arylethyl)-1H-pyrazol-3-ol derivatives are evaluated as anti-bacterial agents.

This article reviews recent electron paramagnetic resonance (EPR) studies on the magnetic properties of nanoparticles of dilute magnetic oxide semiconductors (DMS) doped with transition-metal ions. These nanoparticles are SnO2 doped with Co2+, Fe3+, Cr3+ ions, CeO2 doped with Ni2+, Co2+ ions, and ZnO doped with Fe3+ ions. The EPR studies reveal that the method of synthesis, surface properties, and size of nanoparticles are important factors that determine the magnetic properties of DMS nanoparticles. In addition, they indicate that ferromagnetic and paramagnetic phases may coexist. The saturation magnetization, as estimated from EPR signal, depends both on the doping level of impurities and annealing temperature. Undoped DMS also exhibit ferromagnetism due to oxygen vacancies. Furthermore, the EPR spectrum depends very sensitively on the size of nanoparticle.

A series of C-cinnamoyl glycosides has been synthesized in good yield by the BF3·OEt2 catalyzed aldol condensation of C-glycosylated acetone derivative with a variety of aromatic aldehydes. The synthesized compounds were evaluated for their potential as anti-filarial agents against bovine filarial parasite Setaria cervi and human filariid Wuchereria bancrofti using a number of biological assays such as relative movability (RM) assessment and MTT reduction assay. Among twenty seven test compounds six compounds were found active in terms of MIC, IC50 and LC50 values. Further biological studies were carried out using three lead compounds because of their significantly low MIC values and IC50 values compared to the standard anti-filarial drug Ivermectin. In addition, structure activity relationship study of the test compounds has been carried out using 3D-QSAR analysis.

A wide variety of glycosyl cyanides such as (I) are converted into the corresponding formamide derivatives in water or water/NMP mixtures as the solvent.

Superhalogen species, having the electron affinities higher than that of halogens, play a consequential role in the design of unusual compounds possessing high oxidizing capabilities. Traditionally, such species include a metallic or nonmetallic core with electronegative atoms (F, Cl, and O) or moieties (CN, NCO, and SCN). Note that the electron affinities of these moieties are comparable to or even larger that of F. In the quest for other ligands that might be capable to induce the superhalogen behavior in metal complexes, we have investigated the OF moiety, whose electron affinity is lower than that of F. Utilizing gradient corrected density functional theory, we have systematically studied Au(OF)n complexes (n = 1–6) and their anions. The adiabatic electron affinities of Au(OF)n and vertical detachment energies of Au(OF)n− suggest that these species behave as superhalogens for n ≥ 2. The electron affinities of Au(OF)n, which are smaller than AuFn and Au(CN)n complexes but comparable to that of AuCln, are explained on the basis of extra electron delocalization over several OF moieties. Unlike Au(CN)n (n ≥ 2), which become unstable against dimerization of CN moieties due to their large binding energies, Au(OF)n (n ≤ 4) and Au(OF)n− (n ≤ 5) are found to be stable. The enhanced stability of Au(OF)2− and Au(OF)4− is particularly highlighted. Therefore, the OF moiety is capable of stabilizing the oxidation state of Au up to +4. Note that the highest possible oxidation state of Au is limited to +5. Thus, the investigation advocates that the OF moiety performs better than CN for the stabilization of metal complexes in higher oxidation states. However, the electron affinities of metal complexes stabilized with OF are lower than those with F ligands in accordance with the electronic structure and relatively lower electron affinity of OF.

Among the active galactolipids, compound (I) emerge as lead structure active on both forms of lymphatic filarial parasite, Brugia malayi.

The use of o-nitrobenzyloxycarbonyl (nCbz) for direct protection of exocyclic amino function of nucleosides viz. adenosine, cytidine and deoxyguanosine using o-nitrobenzyl-p-nitrophenyl carbonate as a reagent and O 6 -derivatization of deoxyguanosine with o-nitrobenzyl (nBzl) using o-nitrobenzyldiazomethane as a reagent is being reported. Both these protected groups could be cleaved by irradiation at 354nm to yield valuable building blocks for oligonucleotide synthesis.

The second-order pertubative Moller—Plesset approach, MP2(FC), with a double zeta type basis set for all atoms is used to compute the formation of novel species by the interaction of LiX2 superhalogens with Li2X superalkalies (X: F, Cl, Br, I).

Most of the new indole-containing pseudopeptides (V), (VIII), and (X) possess the optimal range of lipophilicity for oral absorption, cell membrane penetration and blood-brain barrier permeation.

A family of unsymmetrical ferrocenyl-substituted benzothiadiazoles bearing a variety of electron-donating and electron-withdrawing groups, are synthesized by palladium-catalyzed Sonogashira cross-coupling reactions.

This new method to prepare β-glycosyl thiol derivatives in one-step is fast, high yielding, highly stereoselective, and requires only benchtop chemicals.

D-Glucal derivative (I) reacts with alcohols, thiols, and sulfonamides under conditions A) to provide 2,3-unsaturated glycosides with high α-selectivity.

Regioselective ring opening of oxazolones of type (IV) [inter alia precursors of aminocarboxylic acids (II)] by diverse nucleophiles followed by Cu-catalyzed ring closure of resulting enamides provides an efficient approach to various 2-phenyl-4,5-substituted oxazoles.

Carbohydrates (I), (V) and (VIII) are used for the preparation of both types of title compounds, which are suitable for oligosaccharide synthesis.

The acetylation of indole (IIIe) in the presence of AlCl3 leads to desired 3-acetyl derivative (VII), whilst the analogous reaction of 2-tert-butylindoles (IIIa)—(IIId) is accompanied by an unexpected migration of the sulfonyl group.

The activation of glycosyl trichloroacetimidates by nitrosyl tetrafluoroborate provides an alternative to existing protocols for the activation of these compounds in multistep oligosaccharide synthesis.

The electrochemical study of Li2S as cathode material shows that a large potential barrier (1 V) exists at the beginning of the charge process.

A method for preparation of small, drug-like molecules based on indane, tetraline and isoquinoline scaffolds is developed starting from 1,2-bis(bromomethyl)tetrahalobenzenes using Diels—Alder reactions, alkylations and Suzuki couplings.

A rapid and direct access to N-aryl substituted fused triazinone derivatives is accomplished via Cu-mediated N-arylation.

A convenient procedure for preparing some arylureas having herbicidal properties is reported. The method has two steps: (1) reaction of arylamine with chlorocarbonylsulfenyl chloride in the presence of nonpolar solvent to produce aryl carbonylsulfenyl chloride and (2) reaction with dimethylamine in a two-phase reaction catalysed by phase-transfer catalyst to produce the corresponding aryl ureas.

Treatment of per-O-acetylated sugar derivatives with thiols in the presence of boron trifluoride diethyl etherate in an ionic liquid affords the corresponding thioglycosides in good to very good yields.

An eco-friendly reaction protocol allows the preparation of benzylidene acetals (III) of carbohydrate derivatives such as (I) in the presence of a heterogeneous catalyst that replaces hazardous, moisture-sensitive acid catalysts, and by use of a biodegradable solvent.

A new compound library based on the 2-aminochromene framework is synthesized via a novel strategy involving a multi-component reaction and Pd-catalyzed C—C bond forming reaction.

A convenient protocol is developed for the reaction of various glycosyl acetates with, generated in situ.

In the presence of the title catalyst fast and efficient acylation of carbohydrate derivatives, e.g. (I), and free sugars, cf.

A variety of prototype hybrid forms of lupeol is synthesized by chemical modifications of lupeol or lupenone.

A simple, economical and efficient method for the synthesis of the commercially important compounds (IV) is described.

4-Bis(methylthio)methylene-2-phenyloxazol-5-one has been shown to be a versatile template for the synthesis of various 2-phenyl-3,4-substituted oxazoles via nucleophilic ring-opening of oxazolone with various oxygen, nitrogen, and carbon nucleophiles and subsequent 5-endo cyclization of the resulting acyclic adducts in the presence of silver carbonate.

The hydrolysis of differentially functionalized allyl glycosides to their corresponding glycosyl hemiacetal derivatives under mild and metal-free conditions proceeds exceptionally fast and is compatible with most of the functional groups used in oligosaccharide synthesis.

A convergent chemical synthesis of a pentasaccharide found in the O-specific polysaccharide of Escherichia coli O4:K3, O4:K6, and O4:K12 has been achieved in excellent yield. A [3+2] block synthetic strategy has been adopted to couple a disaccharide donor 11 with a trisaccharide acceptor 10 for the construction of the pentasaccharide derivative 12 which on deprotection furnished target pentasaccharide 1 as its 4-methoxyphenyl glycoside. Disaccharide thioglycoside donor 11 and trisaccharide acceptor 10 were prepared from suitably protected monosaccharide intermediates. Yields were excellent in all steps.

Novel mild conditions are developed which are compatible to a broad spectrum of functional groups in oligosaccharide synthesis and can also be applied to thioglycosides and selenium analogues.