O. I. Militsina

Synthesis and anti-tuberculous activity of diesters based on isosteviol and dicarboxylic acids

Diesters based on isosteviol and dicarboxylic acids were synthesized and tested for antituberculous activity. Isosteviol and some of its derivatives exhibit appreciable tuberculostatic properties in vitro, the activity being dependent on the length of the polymethylene spacer connecting two ent-beyeran fragments. The mechanism of the antituberculous action of isosteviol derivatives are discussed.

Reaction of isosteviol diterpenoid with selenium dioxide

Diterpenoid isosteviol was oxidized by selenium dioxide in acetic anhydride or in a mixture of acetic anhydride with dioxane to 15-oxo-derivative, whereas reaction with SeO2 in boiling ethanol led to a mixture of mono- and diselenides. Molecular structure of the monoselenide is established by the X-ray structural analysis.

Synthesis of Schiff bases on the basis of the isosteviol terpenoid

The transformation of the carboxy and keto groups of the isosteviol (ent-16-ketobeyeran-19-oic acid) diterpenoid was used to synthesize its new nitrogen-containing derivatives, including Schiff bases by the C4 and C16 atoms of the isosteviol frame. The structure of the resulting compounds was established by X-ray diffraction.

Alkylation of the isosteviol terpenoid and its oxime with dibromoalkanes in the KOH-DMSO system

The reaction of 16-hydroximinoisosteviol with dihaloalkanes in the KOH-DMSO results in coupling of two isosteviol carcasses by the carboxy groups. The same products were previously synthesized by hydroximination of isosteviol diesters.

Structure of 16-hydroxyisosteviol-derived dicarboxylic acid esters

Dielcometry, method of dipole moments, IR spectroscopy, and computer simulation were used to show that dicarboxylic acid esters derived from 16-hydroxyisosteviol (ent-16-hydroxybeyeran-19-oic acid) exist in CCl4 solutions as tweezer-like or open-chain structures, or dimers with various steric structures, depending on the degree of dilution. Concentrations at which both the esters and parent dicarboxylic acids undergo structural rearrangement were established. The structure of three esters was confirmed by X-ray diffraction.

Unusual course of the reaction of 15(S)-bromoisosteviol methyl ester with sodium azide

The reaction of 15(S)-bromoisosteviol methyl ester with sodium azide produced 15(S)-hydroxyisosteviol, the structure of which was elucidated by an x-ray structure analysis.