Mass spectra of the negative ions of some steroids

It has been shown that the main directions of the fragmentation of the molecular negative ions are connected with the formation of systems of conjugated bonds and the delocalization of the negative charge over a π-system of electrons. The mass spectrometry of the negative ions formed by the dissociative capture of electrons (DCE) is promising for the study of the molecules of steroid compounds.     

New method of preparation of carboxy-protected amino acid conjugates of glycyrrhizinic acid

A method for preparation of carboxy-protected amino acid conjugates of glycyrrhizinic acid with the use of N-hydroxybenzotriazole, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and methyl esters of L-amino acids (phenylalanine, tyrosine, leucine, isoleucine, and methionine) in 85–90% yield was developed. The structure of the prepared compounds was confirmed by IR and ¹³C NMR spectra.     

Beckmann rearrangement of 11-deoxo-glycyrrhetic acid 3-ketoxime

A-Homo-4-aza-3-oxo- and 3-cyano-3,4-seco-olean-4,12-diene derivatives of 11-deoxo-glycyrrhetic acid were synthesized by first- and second-order Beckmann rearrangement of 3-hydroxyiminoolean-12-en-30-oic acid methyl ester.     

Synthesis and anti-HIV-1 activity of new conjugates of 18<Emphasis Type="Italic">β</Emphasis>- and 18<Emphasis Type="Italic">α</Emphasis>-glycyrrhizic acids with aspartic acid esters

New conjugates of 18β- and 18α-glycyrrhizic acids (GAs) each containing two di- or α-methyl esters of L-aspartic acid in the carbohydrate part of the glycosides were synthesized by the activated ester method using the N-hydroxysuccinimide (HOSu) and N,N'-dicyclohexylcarbodiimide. It was found that the conjugate of 18β-GA with Asp(OMe)(OMe) (4) at a concentration of 250 μg/mL inhibited effectively RT of HIV-1 and the accumulation of virus antigen p24 in MT-4 cell culture (95–97 %) and protected cells from the cytopathogenic action of the virus.     

Synthesis and high-resolution NMR spectra of A-nor-derivatives of 11-deoxyglycyrrhetic acid

Several skeletal and oxidative transformations of 11-deoxyglycyrrhetic acid were carried out to produce A-nor-derivatives. Signals for protons and C atoms in the PMR and ¹³C NMR spectra of the A-nor-derivatives were assigned using high-resolution ¹H (400 MHz) and ¹³C (125 MHz) NMR spectroscopy. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 445–448, September–October, 2006.     

Stereoselective synthesis of 2,6-dideoxy-α-l-arabino-hexopyranoside of glycyrrhetic acid in the presence of iodine-containing promoters

Glycosylation of methyl glycyrrhetate withl-rhamnal acetate in the presence of iodine-containing promoters and subsequent hydrogenolysis yield 2,6-dideoxy--l-arabino-hexopyranoside of glycyrrhetic acid, an analog of glycyrrhizic acid, the natural glycoside of licorice root extract.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2993–2996, December, 1996.