Collect. Czech. Chem. Commun.
2006, 71, 387-410
https://doi.org/10.1135/cccc20060387
Preparation and Conformational Study of 19β,28-Epoxy-18α-olean-5-ene Derivatives
Martin Dračínskýa, Václav Richtrb, Václav Křečeka, Jan Sejbala, Jiří Klinota and Miloš Buděšínskýc,*
a Department of Organic Chemistry, Faculty of Science, Charles University, 128 40 Prague 2, Czech Republic
b Department of Chemistry, University of West Bohemia, 306 19 Plzeň, Czech Republic
c Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
Abstract
New oleanane type triterpenoids with the 5(6) double bond were prepared using partial demethylation on carbon C-4. The starting compound was 23-hydroxybetulin (1b) and the key reaction was the methylation of 19β,28-epoxy-24-nor-18α-olean-4-en-3-one (3b). The 5(6) double bond was used in preparation of new derivatives with an epoxy or oxo substituent in ring B. The conformation of ring A of new type 3-oxo oleanane derivatives with a double bond or a substituent on ring B was elucidated from vicinal coupling constants of hydrogen atoms in positions 1 and 2.
Keywords: Triterpenoids; Triterpenes; Oleananes; Lupanes; NMR spectroscopy; Conformation analysis.
References: 46 live references.
