Glycerophosphorylcholine (GPC) is transformed into the cyclic stannylene derivatives, which are selectively acylated to 1-acyl-2-lyso-glycerophosphocholines. The reaction is effective using C-2 to C-16 acid chlorides in 2-propanol. After solvent replacement the lyso-phospholipid (lyso-PL) is subjected to a second acylation using acid anhydrides in methylene chloride. A series of 1(2)-short-2(1)-long-diacyl-glycerophosphocholines are obtained in high yields and selectivity. No diacylation product was detected. In order to detect mixed-chain lipids with inverted disposition of acyl chains, the long chain was introduced first and the thus resulting isomeric compounds compared by NMR. An NMR method was developed in order to determine the positional purity of the isomeric compounds.
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http://dx.doi.org/10.1016/j.chemphyslip.2007.03.008 | DOI Listing |
Anal Chem
December 2024
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China.
Proton (H) NMR spectroscopy presents a powerful tool for biomass mixture studies by revealing the involved chemical compounds with identified ingredients and molecular structures. However, conventional H NMR generally suffers from spectral congestion when measuring biomass mixtures, particularly biomass carbohydrate samples, that contain various physically and chemically similar compounds. In this study, a targeted detection NMR approach, DREAMTIME, is exploited for studying biomass carbohydrate mixtures by spectroscopically targeting the desired compounds in separate 1D NMR spectra.
View Article and Find Full Text PDFBioorg Chem
December 2024
CSIR- Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India. Electronic address:
Alantolactone and isoalantolactone are two isomeric sesquiterpene lactones that were isolated from Innula recemosa. Here, we are used for the semisynthesis of novel isoxazolidine hybrids of alantolactone and isoalantolactone through a two-step process: nitrone synthesis followed by nitrone 1,3-dipolar cycloaddition. The formation of the cycloadduct was well characterized via modern spectroscopic techniques such as HRMS, H NMR, C NMR, DEPT-90, DEPT-135, and 2D NMR.
View Article and Find Full Text PDFMagn Reson Chem
December 2024
Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina, Greece.
Detailed DFT studies of H and C NMR chemical shifts of hydroxy secondary oxidation products of various geometric isomers of conjugated linolenic acids methyl esters are presented. Several low energy conformers were identified for model compounds of the central dienenol OH moiety, which were found to be practically independent on the various functionals and basis sets used. This greatly facilitated the minimization process of the geometric isomers of conjugated linolenic acids methyl esters.
View Article and Find Full Text PDFEnviron Sci Process Impacts
December 2024
Department of Chemistry, University of Toronto, Canada.
Proton transfer reaction mass spectrometry (PTR-MS) is often employed to characterize gas-phase compounds in both indoor and outdoor environments. PTR-MS measurements are usually made without upstream chromatographic separation, so it can be challenging to differentiate between an ion of interest, its isomers, and fragmentation products from other species all detected at the same mass-to-charge ratio. These isomeric contributions and fragmentation interferences can confound the determination of accurate compound mixing ratios, the assignment of accurate chemical properties, and corresponding analyses of chemical fate.
View Article and Find Full Text PDFJ Fluoresc
December 2024
Centre for Nano and Material Sciences, Jain (Deemed-to-be) University, Jain Global Campus, Ramanagaram, Bangalore, 562112, Kanakpuram, Karnataka, India.
In this study, a series of new methoxy ester functionalized core fluorinated, chloro-fluorinated azobenzene derivatives were synthesized. The molecular structures of the azobenzene derivatives (3a-3c and 4a-4c) were confirmed through various analytical methods, with variations in the alkoxy chain length on one end of the aromatic ring. Optical absorption studies of 3a, 3b revealed π-π* transitions around 368-392 nm.
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