Diastereoselective Synthesis of Triterpenoid 1,2,4-Trioxolanes by Griesbaum Co-ozonolysis

Abstract

Diastereoselective synthesis of triterpenoid 1,2,4-trioxolanes by Griesbaum co-ozonolysis was shown for the first time. Ozonolysis of 2-methoxyoximes (syn−anti-isomers mixture) of allobetulin or methyl oleanoate with CF 3 -ketones resulted in asymmetrical spiro-1,2,4-trioxolanes as mixtures of diastereomers in yields up to 80−85%. The configuration of the spiro-C-2 center of individual ozonides was determined by 2D NMR spectra and X-ray crystallographic analysis. The products of ozonolysis of triterpenoid 3-methoxyoximes were mixtures of regioisomeric N-methoxylactams. Thus, the fundamental differences in the oxidation of homologous triterpenoid 2-or 3-methoxyoximes with ozone have been established. These results may afford a new stage in the development of the Griesbaum method as applied to natural compounds and biologically active peroxides.

Expanded scope of Griesbaum co-ozonolysis for the preparation of structurally diverse sensors of ferrous iron

“…To explore this possibility, we evaluated the reaction of enantiopure ketone 2 (ref. 21 ) with a variety of substituted adamantanone oxime substrates under low temperature conditions reported previously 19 for a different substrate ( Table 1 ). We were pleased to find that reactions of 2 with various oximes (3 equiv.)…”

24-Nor-allobetulins possess strong α-glucosidase inhibitory activity

“…Substances were detected by a 10% solution of a sulfuric acid solution with subsequent heating at 100-120°С for 2-3 min. Compounds 1, 8-12 were synthesized according to the methods described in (Dracinsky et al 2006;Flekhter et al 2009;Heller et al 2015;Kazakova et al 2019;Li et al 1998).…”