G. A. Bakaleinik

Glycosides from Stevia rebaudiana

A new laboratory method for isolating the glycosides stevioside and rebaudiosides A and C from leaves of Stevia rebaudiana was proposed. According to HPLC, the glycoside contents in plants grown in Russia (Voronezh Oblast’) and Ukraine (Crimea) were 5–6% (stevioside) and 0.3–1.3% (rebaudiosides A and C).

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.

Chemistry and Structure of Diterpene Compounds of the Kaurane Series: VII. Chiral Complexes of Isosteviol with Aromatic Compounds

Abstract(4α,8β,13β)-13-Methyl-16-oxo-17-norkaurane-18-carboxylic acid (isosteviol) forms with aniline, dimethylaniline, and toluene individual 2:1 molecular complexes whose crystals are isostructural. According to X-ray diffraction data, the supramolecular crystal structure of these complexes is formed by chiral double helices with a 43 screw axis, consisting of isosteviol molecules. The strands of the helices are linked together by intermolecular hydrogen bonds involving the carboxy and carbonyl groups of two isosteviol molecules of neighboring helices. In their turn, the two hydrogen-bonded isosteviol molecules form head-to-tail pseudocage dimers. The aromatic guests occupy fairly large cavities between the strands of isosteviol helices.

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.

Chemistry and Structure of Diterpene Compounds of the Kaurane Series: IV.1 Acylation of Reduction Products of the Isosteviol Keto Group

Acetylation with acetic anhydride of (4α,8β,13β)-16-hydroxy-13-methyl-17-norkaurane-18-carboxylic acid and its methyl ester, obtained by reduction of isosteviol and (4α,8β,13β)-18-methoxycarbonyl-13-methyl-16-oxo-17-norkaurane, respectively, gives rise to (4α,8β,13β)-16-acetoxy-13-methyl-17-norkaurane-18-carboxylic acid and (4α,8β,13β)-16-acetoxy-18-methoxycarbonyl-13-methyl-17-norkaurane. The molecular and crystal structures of the compounds were established by X-ray diffraction.

Chemistry and Structure of Diterpene Derivatives of the Kaurane Series: V. Isosteviol Anhydrides

Abstract(4α,8β,13β)-13-Methyl-16-oxo-17-norkaurane-18-carboxylic acid (isosteviol) anhydride is synthesized, which is a first representative of bisditerpene compounds of the kaurane series. The structures of the anhydride and isosteviol chloride were studies by X-ray diffraction and quantum chemistry (AM1).