Collect. Czech. Chem. Commun. 2006, 71, 1131-1160

Preparation and Conformational Study of B-Ring Substituted Lupane Derivatives

Martin Dračínskýa, Simona Hybelbauerováa, Jan Sejbala and Miloš Buděšínskýb,*

a Department of Organic Chemistry, Faculty of Science, Charles University, 128 40 Prague 2, Czech Republic
b Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic


New lupane-type triterpenoids with 5(6) double bond were prepared using the method of partial demethylation on carbon C-4. Hydroboration of the double bond led to 6α-hydroxy derivative. By the oxidation and following reduction of 6α-hydroxy derivative the 6-oxo and 6β-hydroxy derivatives were prepared. A new method for selective oxidation of secondary hydroxy group in the presence of primary hydroxy group was performed. The conformation of ring A of new lupane-type 3-oxo derivatives with a substituent on ring B was elucidated on the bases of 1H and 13C NMR spectra and molecular modelling.

Keywords: Triterpenoids; Triterpenes; Hydroboration; Oxidation; Lupane; NMR spectroscopy; Conformation analysis.

References: 51 live references.