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Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study
A comprehensive optimization and mechanistic study on the photoinduced hydrothiolation of different d‐ and l‐ hexo‐ and pentoglycals with various thiols was performed, at the temperature range of RT to −120 °C. Addition of thiols onto 2‐substituted hexoglycals proceeded with complete 1,2‐cis‐α‐stere...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900028/ https://www.ncbi.nlm.nih.gov/pubmed/31368604 http://dx.doi.org/10.1002/chem.201903095 |
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author | Kelemen, Viktor Bege, Miklós Eszenyi, Dániel Debreczeni, Nóra Bényei, Attila Stürzer, Tobias Herczegh, Pál Borbás, Anikó |
author_facet | Kelemen, Viktor Bege, Miklós Eszenyi, Dániel Debreczeni, Nóra Bényei, Attila Stürzer, Tobias Herczegh, Pál Borbás, Anikó |
author_sort | Kelemen, Viktor |
collection | PubMed |
description | A comprehensive optimization and mechanistic study on the photoinduced hydrothiolation of different d‐ and l‐ hexo‐ and pentoglycals with various thiols was performed, at the temperature range of RT to −120 °C. Addition of thiols onto 2‐substituted hexoglycals proceeded with complete 1,2‐cis‐α‐stereoselectivity in all cases. Hydrothiolation of 2‐substituted pentoglycals resulted in mixtures of 1,2‐cis‐α‐ and ‐β‐thioglycosides of varying ratio depending on the configuration of the reactants. Hydrothiolation of unsubstituted glycals at −80 °C proceeded with excellent yields and, except for galactal, provided the axially C2‐S‐linked isomers with high selectivity. Cooling was always beneficial to the efficacy, increased the yields and in most cases significantly raised the stereoselectivity. The suggested mechanism explains the different conformational preferences of the intermediate carbon‐centered radicals, which is a crucial factor in the stereoselectivity of the reactions. |
format | Online Article Text |
id | pubmed-6900028 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-69000282019-12-20 Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study Kelemen, Viktor Bege, Miklós Eszenyi, Dániel Debreczeni, Nóra Bényei, Attila Stürzer, Tobias Herczegh, Pál Borbás, Anikó Chemistry Full Papers A comprehensive optimization and mechanistic study on the photoinduced hydrothiolation of different d‐ and l‐ hexo‐ and pentoglycals with various thiols was performed, at the temperature range of RT to −120 °C. Addition of thiols onto 2‐substituted hexoglycals proceeded with complete 1,2‐cis‐α‐stereoselectivity in all cases. Hydrothiolation of 2‐substituted pentoglycals resulted in mixtures of 1,2‐cis‐α‐ and ‐β‐thioglycosides of varying ratio depending on the configuration of the reactants. Hydrothiolation of unsubstituted glycals at −80 °C proceeded with excellent yields and, except for galactal, provided the axially C2‐S‐linked isomers with high selectivity. Cooling was always beneficial to the efficacy, increased the yields and in most cases significantly raised the stereoselectivity. The suggested mechanism explains the different conformational preferences of the intermediate carbon‐centered radicals, which is a crucial factor in the stereoselectivity of the reactions. John Wiley and Sons Inc. 2019-10-01 2019-11-18 /pmc/articles/PMC6900028/ /pubmed/31368604 http://dx.doi.org/10.1002/chem.201903095 Text en © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. |
spellingShingle | Full Papers Kelemen, Viktor Bege, Miklós Eszenyi, Dániel Debreczeni, Nóra Bényei, Attila Stürzer, Tobias Herczegh, Pál Borbás, Anikó Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title | Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title_full | Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title_fullStr | Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title_full_unstemmed | Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title_short | Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl d‐ and l‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study |
title_sort | stereoselective thioconjugation by photoinduced thiol‐ene coupling reactions of hexo‐ and pentopyranosyl d‐ and l‐glycals at low‐temperature—reactivity and stereoselectivity study |
topic | Full Papers |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900028/ https://www.ncbi.nlm.nih.gov/pubmed/31368604 http://dx.doi.org/10.1002/chem.201903095 |
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