The synthesis of 4-deoxy- and 4-deoxy-4-C-methylhexos-5-uloses, starting from 4-deoxyhex-4-enopyranosides, and a nuclear magnetic resonance (NMR) study of their isomeric composition are reported. The NMR spectra show that the two δ-dicarbonyl sugars exist as two anomeric α- and β-oxetanosyl forms, derived from the hemiacetalization of the C-3 hydroxyl group with the aldehydic carbon. The observed tautomeric equilibria have been rationalized with computational calculations. Interestingly, this is the first time that dicarbonyl derivatives are mostly present in their oxetanose forms, offering a new entry into this very interesting type of scaffold.
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http://dx.doi.org/10.1021/jo400953s | DOI Listing |
Molecules
October 2021
Department of Analytical and Environmental Chemistry, Faculty of Sciences, University of Pécs, Ifjúság útja 6, H-7624 Pécs, Hungary.
Lipid A, the membrane-bound phosphoglycolipid component of bacteria, is held responsible for the clinical syndrome of gram-negative sepsis. In this study, the fragmentation behavior of a set of synthetic lipid A derivatives was studied by electrospray ionization multistage mass spectrometry (ESI-MS), in conjunction with tandem mass spectrometry (MS/MS), using low-energy collision-induced dissociation (CID). Genealogical insight about the fragmentation pathways of the deprotonated 4'-monophosphoryl lipid A structural analogs led to proposals of a number of alternative dissociation routes that have not been reported previously.
View Article and Find Full Text PDFJ Org Chem
September 2013
Università di Catania, Dipartimento di Scienze del Farmaco, viale A. Doria 6, I-95125 Catania, Italy.
The synthesis of 4-deoxy- and 4-deoxy-4-C-methylhexos-5-uloses, starting from 4-deoxyhex-4-enopyranosides, and a nuclear magnetic resonance (NMR) study of their isomeric composition are reported. The NMR spectra show that the two δ-dicarbonyl sugars exist as two anomeric α- and β-oxetanosyl forms, derived from the hemiacetalization of the C-3 hydroxyl group with the aldehydic carbon. The observed tautomeric equilibria have been rationalized with computational calculations.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!