Victor Ph. Anufriev

Fluoride salts-alcohols-alumina as reagents for nucleophilic substitution of chlorine atoms for alkoxy groups in 2,3-dichlorosubstituted juglones, naphthazarines, and quinizarines

Abstract Direct displacement of chlorine atoms by alkoxy groups in 2,3-dichlorosubstituted juglones (5-hydroxy-1,4-naphthoquinones), naphthazarines (5,8-dihydroxy-1,4-naphthoquinones), and quinizarines (1,4-dihydroxy-9,10-anthraquinones) is generally ineffective, however high yields are obtained when methanol or cellosolves activated by fluoride anion are used as nucleophiles and the reaction goes in the presence of alumina.

Synthesis of ginsenoside Rg3, a minor constituent of Ginseng Radix

Glycosylation of 12beta-acetoxy-dammar-24-en-3beta,20(S)-diol (4), with hepta-O-acetyl-alpha-sophorosyl bromide (5) under catalysis by Ag2CO3 or Ag2O afforded a chromatographically unseparated mixture of the alpha- and beta-linked octaacetates 6 and 7 in an approximately 2.5:1 ratio. After deprotection and chromatographic purification, the free alpha- (8) and beta-glycosides (9) were obtained. Sophoroside 9 was identical in all respects with ginsenoside Rg3, the minor component of Ginseng Radix rubra. All compounds were fully characterized by 1H and 13C NMR spectroscopy.

A Convenient Method for the Selective Alkylation ofβ-OH Groups of 2(3)-Hydroxyjuglones and Hydroxynaphthazarines

Abstract Trimethyl-and triethylorthoformates have been used for the selective alkylation of β-OH groups of 2(3)-hydroxy-3(2)-alkyljuglones, 2-hydroxy-3-alkyl-, 2-hydroxy-3-chloro-, and 2,3-dihydroxynaphthazarines (1a-o,3,4). In most cases the corresponding alkoxy compounds (2a-q,5,6) were obtained in good yields. However, when 2-hydroxynaphthazarine (1p) was used, the formation of monomethineoxonol derivative (9) as the principal product took place.

The Reductive Dehalogenation of Halo-Substituted Naphthazarins and Quinizarins as a Simple Route to Parent Compounds

Abstract By the reaction of 2-chloro-3-alkyl-, 2,3-dichloro(dibromo)-, trichloro-(tribromo)-and tetrachloro(tetrabromo)-naphthazarins and 2,3-dichloroquinizarin with Fe/HOAc followed by oxidation with an air in a mild basic conditions the corresponding naphthazarins and quinizarin were obtained in good to excellent yields.

Selective Chlorination of Hydroxynaphthazarins with Dichlorine Monoxide. Remarkable Stability of some Geminal Diols Derived from 2,3-Dihydro-2-oxonaphthazarin

Abstract The ration of 2-hydroxynaphthazarins with dichlorine monoxide in CC14 affords the stable gem-diols - 3,3-dichloro-2,3-dihydro-2,2-dihydroxy-paphthazarins in quantitative yields. In the case of 2-hydroxy-3-methyl-iiaphthazarins the formation of the mixture of corresponding monochlorinated at 3 position 2,3-dihydro-3-methyl-2-oxonaphthazarins and 2,3-dihydro-3-methyl-2,2-dihydroxynaphthazarins takes place. For these compounds, under certain conditions, the keto - gem-diol equilibrium is observed.

Direct Displacement of Chlorine Atoms by Alkoxides on Chlorinated Anthraquinones

Abstract The reaction of 1-chloro-, 2-chloro-, 1,5-dichloro-, 1,8-dichloro-, 1-hydroxy-4-chloro-, 1-hydroxy-2,4-dichloro- and 1,4-dihydroxy-5-chloro-9,10-anthraquinones with 2-ethoxyethanol activated by fluoride anion in the presence of alumina affords reasonable to high yields of the corresponding mono- and dialkoxy derivatives.