Resonance assignments of diastereotopic CH2 protons in the anomeric side chain of selenoglycosides by means of 2J(Se,H) spin‐spin coupling constants |
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| Authors: | Yury Yu Rusakov Leonid B Krivdin Ambati Ashok Kumar László Szilágyi Katalin E Kövér |
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| Institution: | 1. A.E. Favorsky Irkutsk Institute of Chemistry, Russian Academy of Sciences, , Irkutsk, Russia;2. Department of Chemistry, University of Debrecen, , Debrecen, Hungary |
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| Abstract: | Unambiguous resonance assignments of diastereotopic CH2 protons in the anomeric side chain of nine alkyl‐ and aralkylselenoglycosides have been carried out on the basis of experimental CPMG‐HSQMBC measurements and theoretical second order polarization propagator approach (SOPPA) calculations of geminal 77Se‐1H spin‐spin coupling constants involving diastereotopic pro‐R and pro‐S protons. Theoretical conformational analyses have been performed at the MP2/6‐311G** level. The conformational space of each of the selenoglycosides under study could be adequately described as a mixture of six interconverting conformers with the molar fractions depending on the nature of the side chain substituent at the selenium atom. The good agreement observed between measured and the weighted conformational averaged values of the calculated coupling constants provides a basis for reliable diastereotopic assignments in this type of carbohydrate structures. Copyright © 2012 John Wiley & Sons, Ltd. |
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| Keywords: | NMR selenoglycosides diastereotopic assignment 77Se‐1H spin‐spin coupling constants SOPPA CPMG‐HSQMBC carbohydrate selenium |
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