Epimerization of C-22 in (25R)- and (25S)-sapogenins
作者:Omar Viñas-Bravo、Penélope Merino-Montiel、Anabel Romero-López、Sara Montiel-Smith、Socorro Meza-Reyes、Francisco J. Meléndez、Jesús Sandoval-Ramírez
DOI:10.1016/j.steroids.2014.10.004
日期:2015.1
Most of the naturally occurring steroidalsapogenins (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. An optimal way to synthesize
Synthesis of steroidal derivatives containing substituted, fused and spiro pyrazolines
作者:Anabel Romero-López、Sara Montiel-Smith、Socorro Meza-Reyes、Penélope Merino-Montiel、José Luis Vega-Baez
DOI:10.1016/j.steroids.2014.05.013
日期:2014.9
through a cycloaddition reaction of different α,β-unsaturatedketones with hydrazine acetate in acetic acid is reported. Depending on the starting material, the ringclosurereaction provided a mixture of two steroidal pyrazoline epimers that were separated and studied by NMR techniques. In one case it was possible to isolate and characterize the hydrazone derivative as the reaction intermediate, which
The one step conversion of the side chain in sapogenins into the 22,26-epoxycholest-22-ene framework was achieved in yields >85% using BF3·OEt2. The new structures maintain the natural chirality at C20 and C25, as shown by X-ray diffraction analyses.
Short Synthesis of New 23-Vinyl Steroid Derivatives from Sapogenins by the Action of 9-BBN on Vinylogous Esters
作者:Jesús Sandoval-Ramírez、Socorro Meza-Reyes、Rosa E. del Rio、Fabiola Reyes- Vazques、Rosa Luisa Santillán、Said Achab、Luis Bohé
DOI:10.1002/ejoc.200400178
日期:2004.8
16β-acetoxy-22,26-epoxy-23-vinylcholest-22-ene steroid derivatives have been synthesized fromsapogenins via a two-step sequence involving the reduction of a vinylogous ester moiety by 9-BBN, a reaction with few precedents and for which a coherent mechanistic interpretation has not been given before now. Some mechanistic insight into this reaction was gained from NMR spectroscopic evidence. A plausible general
Using 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