Cyclopropane formation from 4,5-unsaturated thiophenylethers: Conversion of limonene into car-2-ene

Strong bases can abstract a proton α to double bond. A phenylthio group ψ to that double bond can be eliminated at the same time leading to a cyclopropane ring. The procedure is illustrated by a conversion of limonene into car-2-ene.     

Synthesis of highly substituted pyrrolidines via palladium catalysed formal [2+3] cycloaddition of 5-vinyloxazolidin-2-ones to activated alkenes

Glycine-derived N-tosyl-5,5-divinyloxazolidin-2-one 10 undergoes a palladium catalysed decarboxylative ring-opening cyclization with strongly electron deficient alkylidenemalonate derivatives to give highly substituted pyrrolidines 14 containing two contiguous quaternary centres.     

Les sesquiterpenes bisabolaniques par prenylations acides : une synthese facile de la delabonone et de la 8-EPI-delobanone.

A convenient approach to bisabolane sesquiterpenoids by acid catalysed prenylation of readily available monoterpenes is described.     

Antibacterial Activity and Synergistic Effect of Biosynthesized AgNPs with Antibiotics Against Multidrug-Resistant Biofilm-Forming Coagulase-Negative Staphylococci Isolated from Clinical Samples

Silver nanoparticles form promising template for designing antimicrobial agents against drug resistant pathogenic microorganisms. Thus, the development of a reliable green approach for the synthesis of nanoparticles is an important aspect of current nanotechnology research. In the present investigation, silver nanoparticles synthesized by a soil Bacillus sp. were characterized using UV–vis spectroscopy, FTIR, SEM, and EDS. The antibacterial potential of biosynthesized silver nanoparticles, standard antibiotics, and their conjugates were evaluated against multidrug-resistant biofilm-forming coagulase-negative S. epidermidis strains, S. aureus, Salmonella Typhi, Salmonella Paratyphi, and V. cholerae. Interestingly, silver nanoparticles (AgNPs) showed remarkable antibacterial activity against all the test strains with the highest activity against S. epidermidis strains 145 and 152. In addition, the highest synergistic effect of AgNPs was observed with chloramphenicol against Salmonella typhi. The results of the study clearly indicate the promising biomedical applications of biosynthesized AgNPs.     

LC‐MS analysis of estradiol in human serum and endometrial tissue: Comparison of electrospray ionization,atmospheric pressure chemical ionization and atmospheric pressure photoionization

Accurate measurement of estradiol (E2) is important in clinical diagnostics and research. High sensitivity methods are critical for specimens with E2 concentrations at low picomolar levels, such as serum of men, postmenopausal women and children. Achieving the required assay performance with LC–MS is challenging due to the non‐polar structure and low proton affinity of E2. Previous studies suggest that ionization has a major role for the performance of E2 measurement, but comparisons of different ionization techniques for the analysis of clinical samples are not available. In this study, female serum and endometrium tissue samples were used to compare electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) in both polarities. APPI was found to have the most potential for E2 analysis, with a quantification limit of 1 fmol on‐column. APCI and ESI could be employed in negative polarity, although being slightly less sensitive than APPI. In the presence of biological background, ESI was found to be highly susceptible to ion suppression, while APCI and APPI were largely unaffected by the sample matrix. Irrespective of the ionization technique, background interferences were observed when using the multiple reaction monitoring transitions commonly employed for E2 (m/z 271 > 159; m/z 255 > 145). These unidentified interferences were most severe in serum samples, varied in intensity between ionization techniques and required efficient chromatographic separation in order to achieve specificity for E2. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of chiral stabilised azomethine ylids: A chiral memory relay system.

Chiral, stabilised azomethine ylids incorporated in cyclic templates derived from (R)- or (S)-2-phenylglycinol and (S)-valine undergo enantioselective 1,3-dipolar cycloaddition reactions with a variety of dipolarophiles. Removal of the template in the case of adducts derived originally from (S)-valine furnishes enantiomerically pure -substituted proline derivatives.     

Investigation of statistical,block and graft copolymerizations using nmr-sensitive initiators and macroinitiators

¹³C- and ³¹P-NMR studies on polymers and copolymers derived from ¹³C-enriched AIBN, ¹³C-enriched dibenzyl ketone and diphenyl-2,4,6-trimethylbenzoylphosphine oxide (Lucrin TPO) are reported. They provide information about the influence of solvent on the initiation step in copolymerization reactions, the selectivity of diphenylphosphinyl radicals and the chemical behavior of radicals derived from dibenzyl ketone. In addition, NMR, molecular weight and molecular weight distribution measurements on polymers obtained from polymerizations of methyl methacrylate conducted in the presence of stilbene indicate that stilbene or radicals derived from it may be able to moderate MMA polymerizations.