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
Novel steroidal penta- and hexacyclic compounds derived from 12-oxospirostan sapogenins
作者:José Oscar H. Pérez-Díaz、José Luis Vega-Baez、Jesús Sandoval-Ramírez、Socorro Meza-Reyes、Sara Montiel-Smith、Norberto Farfán、Rosa Santillan
DOI:10.1016/j.steroids.2010.07.008
日期:2010.12
The E ring regioselective acid-catalyzedopening of spirostanic sapogenins possessing a carbonyl group at C-12, such as botogenin and hecogenin, provided the new 12,23-cyclo-22,26-epoxycholesta-11,22-diene skeleton, in addition to new compounds of the already known 12,23-cyclocholest-12(23)-en-22-one frameworks. This transformation proceeds in a single step, under slightly acidic conditions. Both,
E 环区域选择性酸催化打开在 C-12 处具有羰基的螺甾皂苷元,如肉毒杆菌素和 hecogenin,提供了新的 12,23-环-22,26-epoxycholesta-11,22-二烯骨架,此外已知的 12,23-cyclocholest-12(23)-en-22-one 骨架的新化合物。这种转化在弱酸性条件下一步进行。获得了五环和六环类固醇,同时保留了所有不对称中心的构型。