9 research outputs found
Studies in electrophilic cyclization, palladium migration and cationic polymerization
2,3-Disubstituted benzo[b]selenophenes have been prepared by the electrophilic cyclization of various 1-(1-alkynyl)-2-(methylseleno)arenes by Br2, NBS, I2, ICl, PhSeCl, PhSeBr and Hg(OAc) 2. This method tolerates a wide variety of functional groups, including alcohol, ester, nitrile, nitro and silyl groups, and proceeds under exceptionally mild reaction conditions. A cationic intermediate in the cyclization with Br2 has been isolated and studied, providing evidence for a stepwise cyclization process
Studies in electrophilic cyclization, palladium migration and cationic polymerization
2,3-Disubstituted benzo[b]selenophenes have been prepared by the electrophilic cyclization of various 1-(1-alkynyl)-2-(methylseleno)arenes by Br2, NBS, I2, ICl, PhSeCl, PhSeBr and Hg(OAc) 2. This method tolerates a wide variety of functional groups, including alcohol, ester, nitrile, nitro and silyl groups, and proceeds under exceptionally mild reaction conditions. A cationic intermediate in the cyclization with Br2 has been isolated and studied, providing evidence for a stepwise cyclization process.</p
Synthesis and Evaluation of 3-Halobenzo[<i>b</i>]thiophenes as Potential Antibacterial and Antifungal Agents
The global health concern of antimicrobial resistance has harnessed research interest to find new classes of antibiotics to combat disease-causing pathogens. In our studies, 3-halobenzo[b]thiophene derivatives were synthesized and tested for their antimicrobial activities using the broth microdilution susceptibility method. The 3-halo substituted benzo[b]thiophenes were synthesized starting from 2-alkynyl thioanisoles using a convenient electrophilic cyclization methodology that utilizes sodium halides as the source of electrophilic halogens when reacted along with copper(II) sulfate. This environmentally benign methodology is facile, uses ethanol as the solvent, and results in 3-halo substituted benzo[b]thiophene structures in very high yields. The cyclohexanol-substituted 3-chloro and 3-bromobenzo[b]thiophenes resulted in a low MIC of 16 µg/mL against Gram-positive bacteria and yeast. Additionally, in silico absorption, distribution, metabolism, and excretion (ADME) properties of the compounds were determined. The compounds with the lowest MIC values showed excellent drug-like properties with no violations to Lipinski, Veber, and Muegge filters. The time-kill curve was obtained for cyclohexanol-substituted 3-chlorobenzo[b]thiophenes against Staphylococcus aureus, which showed fast bactericidal activity at MIC
Divinylanthracene-Containing Tetracationic Organic Cyclophane with Near-Infrared Photoluminescence
Near-infrared
(NIR) light is known to have outstanding optical
penetration in biological tissues and to be non-invasive to cells
compared with visible light. These characteristics make NIR-specific
light optimal for numerous biological applications, such as the sensing
of biomolecules or in theranostics. Over the years, significant progress
has been achieved in the synthesis of fluorescent cyclophanes for
sensing, bioimaging, and making optoelectronic materials. The preparation
of NIR-emissive porphyrin-free cyclophanes is, however, still challenging.
In an attempt for fluorescence emissions to reach into the NIR spectral
region, employing organic tetracationic cyclophanes, we have inserted
two 9,10-divinylanthracene units between two of the pyridinium units
in cyclobis(paraquat-p-phenylene). Steady-state absorption,
fluorescence, and transient-absorption spectroscopies reveal the deep-red
and NIR photoluminescence of this cyclophane. This tetracationic cyclophane
is highly soluble in water and has been employed successfully as a
probe for live-cell imaging in a breast cancer cell line (MCF-7)