Collect. Czech. Chem. Commun. 1991, 56, 886-904

Anhydrobetulin and its derivatives

Alois Vystrčila, Václav Křečeka, Jiří Protivaa and Miloš Buděšínskýb

a Department of Organic Chemistry, Charles University, 128 40 Prague 2
b Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


The structure of anhydrobetulin II and its derivatives I, III and IV has been solved using 1H and 13C NMR spectra, mass spectra and chemical transformations. It has been proven that in addition reactions the trisubstituted double bond is attacked selectively from the α-side under formation of D/E cis-annelated derivatives VIII, X and XI. The 22-oxo derivative XIII exhibits an anomalous Cotton effect and, in contrast to its saturated analogue XXVII,it is not epimerized in alkaline medium. Trinordiketone XXI easily epimerizes to a mixture in which the 17βH-epimer XXIb predominates, trinorketone XXIV is stable only if the annelation of rings D and E is trans. These differences are explained in terms of steric interactions of substituents in position 19. The steric course of reduction of ketones XIII and XXIV with sodium borohydride is described.