3/9/2023 0 Comments Rapidclick download![]() The formation of all products can be rationalized by a mechanism which includes an initial carbon-carbon bond formation involving the central allene carbon to give a diradical intermediate. Stepwise bonding prefers to occur in a 1,6-exo manner rather than in a 1,7-endo fashion. Only the C-1-C-2 double bond of the allene participates in the -cycloaddition. ![]() The thermal reactions of these phenylsulfonyl allenes gave -cycloadducts. The reaction proceeds by initial attack of the soft carbanion onto the terminal position of the diene and subsequent PhSO(2)(-) elimination to give the phenylsulfonyl substituted. The reaction of a series of allyl-substituted bis(phenylsulfonyl)methanes or dimethyl malonates with 2,3-bis(phenylsulfonyl)-1,3-butadiene in the presence of base afforded alkenyl-substituted allenes in good yield. ![]() The on-surface tobacco-specific nitrosamines (TSNAs), such as 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal) (NNA), 4-(methylnitrosamino)-1-(3-pyridinyl)-1-butanone (NNK), and N-nitroso nornicotine (NNN) were in-situ successfully detected in dust samples. Smoking-related biomarkers analyses in urine were accomplished, with a 10-second DCBI analysis time. Low-temperature DCBI-MS/MS was applied to the direct detection of THS on fingers without any skin damage. The limits of detection of nicotine and cotinine were both 1.4 μg m⁻². nicotine and cotinine on different surfaces such as fruits, cotton clothing, glass, and toys etc. To this end, an in-situ DCBI-MS/MS approach was developed for the quantitative analysis of typical THS environmental markers, i.e. The aim of this study is to establish desorption corona beam ionization (DCBI)-MS/MS as an analytical tool for THS research. Because THS components have properties of remaining on, re-emitting from and reacting on and with surfaces, in-situ analysis of the components on different surfaces is both in high demand and challenging. Third-hand smoke (THS) is composed of surface-deposited remnants resulting from tabacco-smoking. Click chemosensing addresses increasingly important time efficiency, cost, labor and chemical sustainability aspects and streamlines asymmetric reaction development at the mg scale. The ruggedness and practicality of this approach are demonstrated by comprehensive analysis of nonracemic monoamine samples and crude asymmetric imine hydrogenation mixtures without work-up. This method has several attractive features, including wide scope, fast substrate fixation without by-product formation or complicate equilibria often encountered in reversible substrate binding, excellent solvent compatibility, and tolerance of air and water. Herein, we report the use of a readily available coumarin conjugate acceptor for chiroptical click chirality sensing of the absolute configuration, concentration and enantiomeric excess of several compound classes. Despite the progress with optical sensors that exploit the principles of dynamic covalent chemistry, metal coordination or supramolecular assemblies, quantitative analysis of complex mixtures remains challenging. The inherent robustness and practicality of click chemistry encouraged us to explore probe designs that overcome drawbacks of currently used chiroptical sensing methods such as limited substrate scope (amine sensors often utilize reversible Schiff base formation and are restricted to primary substrates), competing chiral recognition processes and equilibria that complicate the analysis and diminish CD readouts, and sensitivity to moisture, air, and other chemical interferences, which limits the usefulness when complex mixtures need to be examined.Ĭlick reactions have become powerful synthetic tools with unique applications in the health and materials sciences. Since then, a variety of reaction strategies and applications that exploit this concept, in particular in the biomedical domain, have been introduced. More than 10 years ago, Sharpless coined the term "click chemistry" for reactions that are high yielding, practical and operationally safe, avoid by-product formation, proceed in environmentally benign solvents at room temperature and generally under mild conditions, and eliminate chromatographic work-up 20.
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