The Solid-State and Solution-State Reassigned Structures of Tagitinin A, a 3,10-Epoxy-Germacrolide from Tithonia diversifolia, and the Interconversion of 3,10-Epoxy-Germacrolide Conformational Families via a Ring-Atom Flip Mechanism
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| Format: | Artículo científico |
| Langue: | en |
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Sociedad Química de México
2005
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| _version_ | 1876435918108229632 |
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| author | Robert Glaser |
| author_facet | Robert Glaser |
| contents | The Solid-State and Solution-State Reassigned Structures of Tagitinin A, a 3,10-Epoxy-Germacrolide from Tithonia diversifolia, and the Interconversion of 3,10-Epoxy-Germacrolide Conformational Families via a Ring-Atom Flip Mechanism Robert Glaser Abraham García María Isabel Chávez Guillermo Delgado Multidisciplinaria (Ciencias Naturales y Exactas) tagitinin A Horeaus rule molecular modeling conformational interconversion Tagitinin A (2), a known 3,10-epoxy-germacrolide-6,7-trans-lactone isolated from Tithoniadiversifolia, was investigated by single crystal X-ray diffraction analysis. It was found to have a1β,4α,6α,7β,8β relative configuration which differed at C(1) from the 1α-orientation originallyreported in the literature which was determined by Horeaus Rule. Analysis of the 1H NMR spectrumof 2 shows the molecule to maintain its crystallographically observed twist-chair-boat (TCB) ninememberedring conformation in acetone-d6 solution. The twist-chair-boat/skew-chair-boat type 3conformations of saturated/unsaturated nine-membered rings within 3,10-epoxy-germacrolides canbe interconverted to the skew-chair-chair (SCC) conformation by means of a C(9) ring atom flipmechanism. As a result of this conformational change, the orientation of the C(1) atom and the C(8)-oxycarbonyl moiety are transformed from diequatorial to diaxial. The reported stereochemistry of3,10-epoxy-germacrolide lactone structures, and the DFT B3LYP/6-31g(d) modeling findings inthis work indicate that tetrahedral C(1) atoms stabilize the TCB/SCB type 3 conformations, whiletheir trigonal counterparts stabilize the SCC conformation. 2005 artículo científico 1870-249X https://www.redalyc.org/articulo.oa?id=47549219 en http://www.redalyc.org/revista.oa?id=475 Journal of the Mexican Chemical Society application/pdf Sociedad Química de México Journal of the Mexican Chemical Society (México) Num.2 Vol.49 |
| format | Artículo científico |
| id | redalyc_47549219 |
| institution | Redalyc |
| language | en |
| publishDate | 2005 |
| publisher | Sociedad Química de México |
| spellingShingle | The Solid-State and Solution-State Reassigned Structures of Tagitinin A, a 3,10-Epoxy-Germacrolide from Tithonia diversifolia, and the Interconversion of 3,10-Epoxy-Germacrolide Conformational Families via a Ring-Atom Flip Mechanism Robert Glaser Multidisciplinaria (Ciencias Naturales y Exactas) tagitinin A Horeaus rule molecular modeling conformational interconversion The Solid-State and Solution-State Reassigned Structures of Tagitinin A, a 3,10-Epoxy-Germacrolide from Tithonia diversifolia, and the Interconversion of 3,10-Epoxy-Germacrolide Conformational Families via a Ring-Atom Flip Mechanism Robert Glaser Abraham García María Isabel Chávez Guillermo Delgado Multidisciplinaria (Ciencias Naturales y Exactas) tagitinin A Horeaus rule molecular modeling conformational interconversion Tagitinin A (2), a known 3,10-epoxy-germacrolide-6,7-trans-lactone isolated from Tithoniadiversifolia, was investigated by single crystal X-ray diffraction analysis. It was found to have a1β,4α,6α,7β,8β relative configuration which differed at C(1) from the 1α-orientation originallyreported in the literature which was determined by Horeaus Rule. Analysis of the 1H NMR spectrumof 2 shows the molecule to maintain its crystallographically observed twist-chair-boat (TCB) ninememberedring conformation in acetone-d6 solution. The twist-chair-boat/skew-chair-boat type 3conformations of saturated/unsaturated nine-membered rings within 3,10-epoxy-germacrolides canbe interconverted to the skew-chair-chair (SCC) conformation by means of a C(9) ring atom flipmechanism. As a result of this conformational change, the orientation of the C(1) atom and the C(8)-oxycarbonyl moiety are transformed from diequatorial to diaxial. The reported stereochemistry of3,10-epoxy-germacrolide lactone structures, and the DFT B3LYP/6-31g(d) modeling findings inthis work indicate that tetrahedral C(1) atoms stabilize the TCB/SCB type 3 conformations, whiletheir trigonal counterparts stabilize the SCC conformation. 2005 artículo científico 1870-249X https://www.redalyc.org/articulo.oa?id=47549219 en http://www.redalyc.org/revista.oa?id=475 Journal of the Mexican Chemical Society application/pdf Sociedad Química de México Journal of the Mexican Chemical Society (México) Num.2 Vol.49 |
| title | The Solid-State and Solution-State Reassigned Structures of Tagitinin A, a 3,10-Epoxy-Germacrolide from Tithonia diversifolia, and the Interconversion of 3,10-Epoxy-Germacrolide Conformational Families via a Ring-Atom Flip Mechanism |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) tagitinin A Horeaus rule molecular modeling conformational interconversion |
| url | https://www.redalyc.org/articulo.oa?id=47549219 |