Facile conversion of spirostan saponin into furostan saponin: synthesis of methyl protodioscin and its 26-thio-analogue

[reaction: see text] A facile approach for the conversion of a spirostan saponin into its furostan counterpart, as illustrated by the transformation of dioscin to methyl protodioscin (and its 26-thio-analogue), has been developed.     

Synthesis and biological activity of methyl derivatives of dl-19-nor-D-homotestosterone

Summary The synthesis of racemates of the 2-methyl, 4-methyl, 17-methyl, and 2, 17-dimethyl derivatives of 19-nor-D-homotestosterone has been described. Biological tests have shown that the introduction of a CH₃ group into positions 2 and 17 totally suppresses both androgenic and anabolic activity. The introduction of a CH₃ group into position 4 leads to a divergence of the anabolic and androgenic effects.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 1, pp. 3–9, 1968     

Methyl α- -fructofuranoside: Synthesis and conversion into carboxylates

Methyl α- -fructofuranoside was synthesized by methylation of -fructose and subsequent isolation of the α-furanoside from the anomeric mixture. This fructofuranoside was used as a starting material for the syntheses of several carboxylates, applying glycolic oxidation, selective oxidation of the primary alcohol function at the C-6 position and carboxymethylation.     

Synthesis of methylvinylpolyfluoroalkoxysilanes by photoinitiated radical reaction of dialkoxy(methyl)vinylsilanes with perfluoro-4-methylpent-2-ene

A new method was elaborated for the synthesis of vinylsilanes with polyfluoroalkoxy substituents at the silicon atom using the photoinitiated radical reaction of dialkoxy(methyl)vinylsilanes with perfluoro-4-metliylpent-2-ene in the presence of di-tert-butyl peroxide at room temperature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2976–2978, December, 1996,     

Synthesis of acrylates based on tetracyclododecene and its methyl derivative

The reaction of catalytic and thermal addition of acrylic acid to tetracyclo[4.4.1^2,5.1^7,10.0^1,6]dodec-3-en and its 8-methyl-substituted derivative was studied. The reaction is intended for the synthesis of corresponding acrylates, which are reactive monomers suitable for producing high-molecular compounds.     

Synthesis of a novel silicon-bridged [2.2]metacyclophan-9-ene and its photolytic transannular reaction

A novel [2.2]metacyclophane in which two benzene rings are linked together with a carbon-carbon double bond and a disilane unit was prepared. Photolysis of the cyclophane in the presence of oxygen afforded the 4,5-dihydro-4,5-disilapyrene derivative via a transannular dehydrogenation reaction.     

Penicillium sclerotiorum catalyzes the conversion of herbertenediol into its dimers: mastigophorenes A and B

Herbertenediol was subjected to biotransformation by Penicillium sclerotiorum. Spectral data analysis of the converted metabolites revealed that the neurotrophic active compounds, mastigophorenes A and B, dimeric to the substrate were formed.     

Synthesis of benzo[b]selenophene and its methyl homologs

A method for the synthesis of benzo[b]selenophenes was perfected. 3-Oxo-2,3-dihydrobenzo[b]selenophene and 2-methyl-3-oxo-2,3-dihydrobenzo[b]selenophene exist only in the keto form. 3-Methylbenzo[b]selenophene was obtained by the reaction of 3-oxo-2,3-dihydrobenzo[b]selenophene with methylmagnesium iodide. Metallation of benzo[b]selenophene with butyllithium proceeds at the 2 position of the selenophene ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1480, November, 1970.     

Synthesis of imidazolidin-4-ones and their conversion into 1,4-benzodiazepin-2-ones

α-Haloacetanilides Ia-e react with hexamine in ethanol giving the bisimidazolidin-4-one derivatives IIa-e, which hydrolize, in acidic media into the corresponding mono-imidazolidin-4-ones IIIa-e. The compounds IIa-d were converted into 1,4-benzodiazepin-2-ones, under different conditions and in the presence of a variety of agents. The yields were between 50 and 100%.     

ESR studies on the conversion of mechanoradicals of poly(methyl methacrylate) and its self-degradation

Mechanisms of the conversion of poly(methyl methacrylate) (PMMA) radicals produced by ball-milling have been investigated by means of ESR. The spectrum observed after a short milling time (0·1 h) at 77 K in vacuum was resolved into the three components, a triplet, a nonet and a doublet. The nonet, the triplet and the doublet are ascribed to the three kinds of radical:

respectively. On the other hand, it was found that the spectrum after milling for more than 18 h at 77 K in a vacuum consisted of the nonet and the doublet, which had been converted from the triplet. The conversion of the triplet to the doublet during long milling suggests inter- and/or intra-hydrogen abstraction by the radical responsible for the triplet.The doublet observed after milling for longer than 18 h did not change its line-shape up to 263 K but on further warming to 273 K for 0·1 h the spectrum changed to give a triplet component. This reproduction of the triplet was interpretated in terms of β-bond scission to the unpaired electron of the radical (C), due to the thermal treatment. The bond scission was confirmed by the observed decrease in the molecular weight after the heat treatment. The radical (B) formed by the β-scission abstracts the hydrogen in the PMMA parent molecule to produce a radical of the species (C). This cyclic reaction leads to a self-degradation.     

Synthesis of 11-aminodrim-7-ene from drimenol

11-Aminodrim-7-ene was synthesized from drimenol in four steps. Drimenol was oxidized into drimenal and its oxime was dehydrated by p-tosylchloride or acetic anhydride in pyridine to form 9-cyano-11-nordrim-7-ene, reduction of which by LiAlH₄ in the presence of anhydrous AlCl₃ produced 11-aminodrim-7-ene. The reaction of 9-cyano-11-nordrim-7-ene, NaBH₄, and CoCl₂·6H₂O produced a mixture of drimenylamine and 7,8-dihydrodrimenylamine in a 2:1 ratio. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 311–314, May–June, 2009.     

Identification of phenols of 7,12-dimethylbenz[a]anthracene by conversion into their methyl ethers

The compound 7,12-dimethylbenz[a]anthracene (DMBA), a powerful chemical carcinogen, undergoes enzymatic oxidation to a variety of metabolites. Phenols, the monohydroxylated derivatives of DMBA, are an electrophilic species capable of binding covalently with DNA. Although phenols may play a role in carcinogenesis, little information is available regarding these metabolites, many of which are chemically unstable and elusive to quantitative analysis. In this study, a method is described for the methylation of phenolic products to their chemically stable methyl ether derivatives. Application of this procedure to in vitro incubations of DMBA with rat liver microsomes resulted in the isolation and identification of 4-hydroxy DMBA, 8-hydroxy DMBA and 3-hydroxy DMBA.     

Synthesis of E-deoxypukalide, and its biomimetic conversion into deoxypseudopterolide by photochemical ring contraction involving a 1,3-allylic shift

Irradiation of a solution of synthetic Z-deoxypukalide 10 in acetonitrile (Pyrex; 400 W Hg lamp) resulted in isomerisation, leading to E-deoxypukalide 12, which was isolated recently from the octocoral Leptogorgia spp. Further irradiation of 12, or prolonged irradiation of 10, then gave the ring-contracted product, deoxypseudopterolide 1 (>90%) found in octocorals of the genera Pseudopterogorgia and Leptogorgia. The contraction of the 14-membered rings in 10 and 12 to the 12-membered ring as 1, occurs by way of photochemical [1,3]-sigmatropic rearrangement.