Synthesis of 5-Aryl-1,4-naphthoquinone and 1-Aryl-9,10-anthraquinone Derivatives by Cycloaddition of 1-(Dimethoxyphenyl)-3-trimethylsiloxy-1,3-butadienes to 1,4-Benzoquinones and 1,4-Naphthoquinones

The Diels-Alder reaction of new 1-(3,4-dimethoxyphenyl)- or 1-(2,4-dimethoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2,5- and 2,6-dibromo-, and 2-bromo-6-methyl-1,4-benzoquinones regioselectively yields substituted 7-hydroxy-5-(dimethoxyphenyl)-1,4-naphthoquinones. By cycloaddition of the siloxydienes to naphthoquinone, bromonaphthoquinone, and juglone the corresponding substituted 3-hydroxy-1-(dimethoxyphenyl)-9,10-anthraquinones or their 4,4a-dihydro or 1,1a,4,4a-tetrahydro derivatives were obtained.     

Synthesis of Betulonic Acid Derivatives Containing Amino-Acid Fragments

New derivatives of betulonic acid containing on C-28 fragments of amino acids or their methyl esters were prepared as potential biologically active agents.     

Synthesis of 30-Amino Derivatives of Lupane Triterpenoids

New derivatives of betulin and betulinic acid containing various amines on C-30 that are of interest as potentially biologically active agents were prepared. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 571–577, November–December, 2005.     

Synthetic Transformations of Higher Terpenoids: VIII. [4+2]-Cycloaddition Reactions of Lambertianic Acid

The Diels-Alder reaction of lambertianic acid with maleic anhydride occurred in a stereoselective fashion and yielded diastereoisomeric (1R,2S,6R,7R)- and (1S,2R,6S,7S)-exo-adducts. The latter reacted with L-valinol to give the corresponding diterpenoid imides, 4-aza-9-oxabicyclo[2.2.1]dec-8-enes. Reactions of lambertianic acid with N-substituted maleimides in the presence of Lewis acids afforded diastereoisomeric adducts having both exo and endo configuration. Some transformations of the adducts were examined with a view to obtain cantharidin and dihydroisoindole analogs.     

Synthetic Transformations of Higher Terpenoids: VII. Synthesis of Tetrahydro-β-carbolines of the Labdane Series

Reductive amination of methyl 16-formyllambertianate with tryptamine, followed by Pictet-Spengler cyclization of the resulting diterpenoindole amine with formaldehyde, yields methyl 16-(1,2,3,4-tetrahydro--carbolin-2-ylmethyl)lambertianate. The reaction of formyl-substituted methyl labdatrienoates and labdadienoates with 2-(3-indolyl)ethylamines provides a convenient approach to 1-diterpeno--carbolines.     

Isolation and Chemical Transformations of Vasicinone

Vasicinone and peganine were isolated from Peganum harmala L. Vasicinone 2,4-dinitrophenylhydrazone and vasicinone ketal were prepared.     

Xanthones from <Emphasis Type="Italic">Halenia corniculata</Emphasis>. 3. Preparation of Standard 1-Hydroxy-2,3,4,5-tetramethoxyxanthone

1-Hydroxy-2,3,4,5-tetramethoxyxanthone, which is used as a standard for quantitative determination of the total content of γ-pyrones, was isolated from the aerial part of Halenia corniculata L. Cornaz., an available raw material in Russia. A method for preparing standard 1-hydroxy-2,3,4,5-tetramethoxyxanthone was developed. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 420–421, September–October, 2005.