α,α‐Dibromoketones: A Superior Alternative to α‐Bromoketones in Hantzsch Thiazole Synthesis

Abstract

α,α‐Dibromoketones (2) have been found to be a superior alternative to the conventionally used α‐bromoketones (1) for performing the Hantzsch thiazole synthesis.1 Ahluwalia, V. K., Mehta, B. and Rawat, M. 1992. Synth. Commun., 22: 2697[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar] These crystalline, nonlachrymatory compounds are more reactive than 1 as demonstrated by their reaction with 3,5‐dimethyl‐1‐thiocarboxamide (5).     

Synthesis of 3-(arylamino)-5-bromo-2-phenyl-2,3-dihydro-2λ5-benzo[d][1,2]-oxaphosphol-2-oxides

An efficient synthesis of cis-3-(arylamino)-5-bromo-2-phenyl-2,3-dihydro-2λ⁵-benzo[d][1,2]-oxaphosphol-2-oxides 4a–h is described involving a three-component reaction of dichlorophenylphosphine (2), 5-bromosalicylaldehyde (1), and different substituted aromatic primary amines (3) in anhydrous benzene. The product structures were characterized by IR and NMR spectral data.     

Polymer Supported Vanadium Salt as a Catalyst for the Oxidation of Phenols

Oxidation of substituted phenols to the corresponding quinones are reported using a novel macroporous polymer bound catalyst. The catalyst provides a good conversion and is recyclable.     

Xanthan Sulfuric Acid: An Efficient,Biosupported, and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′-(Arylmethylene)bis(1H-pyrazol-5-ols)

A simple and efficient method has been developed for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by the condensation reaction between substituted aldehydes, and 1-phenyl-3-methylpyrazol-5-one in the presence of xanthan sulfuric acid (XSA) as a solid acid catalyst. This method is simple and cost-effective with short reaction times. Yields are excellent with high purity, and the catalyst could be easily recycled.     

Iodobenzene Diacetate Mediated Oxidation of N-Substituted Hydrazones of Chalcones: An Efficient Regioselective Synthesis of 1,3,5-Trisubstituted Pyrazoles

Iodobenzene diacetate, a relatively benign nonmetallic oxidant, has been utilized efficiently for the oxidation of N-substituted hydrazones of chalcones to afford 1,3,5-trisubstituted pyrazoles under mild reaction conditions.     

LiBr: A Mild Lewis Acid Catalyst for Efficient One-Pot Synthesis of α-Amino Nitriles

α-Amino nitriles are synthesized in a one-pot, three-component coupling of aldehydes, amines, and trimethylsilyl cyanide using a catalytic amount of LiBr at ambient temperature.     

Uniform waveband assignment in optical mesh networks

The cost of an optical network in wavelength division multiplexing (WDM) networks can be reduced using optical reconfigurable optical add/drop multiplexers (ROADMs), which allow traffic to pass through without the need for an expensive optical-electro-optical (O-E-O) conversion. Waveband switching (WBS) is another technique to reduce the network cost by grouping consecutive wavelengths and switching them together using a single port per waveband. WBS has attracted the attention of researchers for its efficiency in reducing switching complexity and therefore cost in WDM optical networks. In this paper, we consider the problem of switching wavelengths as non-overlapping uniform wavebands, per link, for mesh networks using the minimum number of wavebands. Given a fixed band size b _s , we give integer linear programming formulations and present a heuristic solution to minimize the number of ROADMs (number of wavebands) in mesh networks that support a given traffic pattern. We show that the number of ROADMs (or number of ports in band-switching cross-connects) can be reduced significantly in mesh networks with WBS compared to wavelength switching using either the ILP or the heuristic algorithm. We also examine the performance of our band assignment algorithms under dynamic traffic.     

Pathophysiological Role and Medicinal Chemistry of A2A Adenosine Receptor Antagonists in Alzheimer’s Disease

The A_2A adenosine receptor is a protein belonging to a family of four GPCR adenosine receptors. It is involved in the regulation of several pathophysiological conditions in both the central nervous system and periphery. In the brain, its localization at pre- and postsynaptic level in striatum, cortex, hippocampus and its effects on glutamate release, microglia and astrocyte activation account for a crucial role in neurodegenerative diseases, including Alzheimer’s disease (AD). This ailment is considered the main form of dementia and is expected to exponentially increase in coming years. The pathological tracts of AD include amyloid peptide-β extracellular accumulation and tau hyperphosphorylation, causing neuronal cell death, cognitive deficit, and memory loss. Interestingly, in vitro and in vivo studies have demonstrated that A_2A adenosine receptor antagonists may counteract each of these clinical signs, representing an important new strategy to fight a disease for which unfortunately only symptomatic drugs are available. This review offers a brief overview of the biological effects mediated by A_2A adenosine receptors in AD animal and human studies and reports the state of the art of A_2A adenosine receptor antagonists currently in clinical trials. As an original approach, it focuses on the crucial role of pharmacokinetics and ability to pass the blood–brain barrier in the discovery of new agents for treating CNS disorders. Considering that A_2A receptor antagonist istradefylline is already commercially available for Parkinson’s disease treatment, if the proof of concept of these ligands in AD is confirmed and reinforced, it will be easier to offer a new hope for AD patients.     

Chalcone as Anode Material for Aqueous Rechargeable Lithium-Ion Batteries

Russian Journal of Electrochemistry - Utilization of environmental friendly, potentially sustainable, low cost, high capacity organic electrode materials seem to be very promising for next...     

Metal-free multicomponent synthesis and in vitro antioxidant activity of indolylpyrazolopyrimidines

Multisubstituted indolylpyrazolopyrimidines were synthesized in good yields with base promoted one-pot multicomponent system from aldehyde, ketone, and indolylpyrazolamine. Milder and cost-effective conditions are the highlights of the present protocol. Among the synthesized compounds ( 4a-j ) 4b , 4c , 4e , and 4f have shown significant better in vitro antioxidant activity compared to standard ascorbic acid.