Herein we report an unprecedented and efficient methodology for accessing 6-alkoxy-Δ-diene-3-one derivatives. Such scaffolds were serendipitously obtained in the course of the study of the reaction of Δ-3-keto steroids with catalytic amounts of iodine in refluxing methanol. A series of 6-methoxy and 6-ethoxy- Δ-diene-3-ones were prepared from easily-available sterols in a two-step sequence; first, oxidation of sterols furnished the Δ-3-keto steroids, which were then refluxed with ethanol or methanol with I as catalyst to obtain a series of ten derivatives.
View Article and Find Full Text PDFGreen synthesis may be a useful approach to achieve selective cytotoxicity of silver nanoparticles on cancer cells and healthy cells. In this study, the concomitant biosynthesis of silver (Ag)/silver chloride (AgCl) nanoparticles from pineapple peel extracts and their behavior on the breast cancer cell line MCF-7 is shown. Bioreactions were monitored at different temperatures.
View Article and Find Full Text PDFUsing cholesterol and diosgenin as starting materials, we have designed a straightforward methodology to prepare in a reduced number of steps a novel series of steroidal oximes and their aza-homolactam analogs with four types of side chains: cholestane, spirostane, 22-oxocholestane and 22,26-epoxycholestene. The products were evaluated for their cytotoxic activity against the MCF-7 breast cancer cell line. Moreover, the selectivity of the most active compounds was determined against peripheral blood lymphocytes.
View Article and Find Full Text PDFMost of the naturally occurring steroidal sapogenins (C-23 non-substituted frameworks), possess an R configuration at the spiro C-22 center. Their C-22 epimers have become important targets in biological research. This paper describes a procedure to obtain 22S-spirostans from 22R-sapogenins and pseudosapogenin skeletons, without affecting the chirality at either C-25 or C-20.
View Article and Find Full Text PDFWe report a facile protocol to obtain 22-substituted furostans and pseudosapogenins in high yields from (25R)- and (25S)-sapogenins. This method involves the treatment of the sapogenin with acetic-trifluoroacetic mixed anhydride and BF(3)·OEt(2) at room temperature, followed by the addition of a nucleophile (H(2)O, MeOH or KSeCN). In the case of 22-hydroxyfurostans, they can be transformed to pseudosapogenins by treatment with p-toluensulfonic acid.
View Article and Find Full Text PDF(1)H and (13)C NMR spectroscopic data for 5alpha-androstanes and halo-5alpha-androstanes with different substituents at positions C-3, C-9, C-11 and C-17 were examined and assigned by a combination of 1D and 2D NMR experiments. The substituent effects on the (13)C chemical shifts were compared with those of epi-androsterone, used as a reference compound. The coupling constants (n)J((19)F,(13)C) were measured for compounds 6, 8, 11 and 14.
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