Collect. Czech. Chem. Commun.
1993, 58, 2505-2516
https://doi.org/10.1135/cccc19932505
Oxidation of 3β,28-Diacetoxy-18-lupen-21-one with Peroxy Acids: A Way to Des-E-lupane Derivatives
Eva Klinotováa, Martin Rejzeka, Hana Zůnováa, Jan Sejbala, Jiří Klinota and Jiří Urbanb
a Department of Organic Chemistry, Charles University, 128 40 Prague 2, Czech Republic
b J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic
Abstract
Oxidation of 3β,28-diacetoxy-18-lupen-21-one (I) and its 18β, 19β-epoxy derivative III with peracetic acid, catalyzed with strong acids, proceeds with cleavage of the bond between C-19 and C-21 under formation of E-seco derivatives with hydroxyl and isobutyryl groups on C-18 (spiro lactones V - VII and acid VIII). Oxidative removal of the isobutyryl fragment in spiro lactone VI by treatment with lead tetraacetate leads to the tetranor derivative - keto lactone XI which in an alkaline medium loses formaldehyde from C-17 to give des-E acid XVI.
