A Grignard reagentinduced tandem semipinacol rearrangement/chelation-controlled ketone addition process, which converts 20S-hydroxy-5α-pregnane-16(17)-epoxide into an unusual C20-substituted 17S-pregnane-3S,16R,20S-triol, is described.
Baeyer-Villiger reaction of steroid sapogenins by CF 3 COOH-H 2 O 2 . A short cut to pregnan-3β,16β,20-triol 3-monoacetates
作者:Katherine Vargas-Romero、Oscar Alberto、Marcos Flores-Álamo、Martín A. Iglesias-Arteaga
DOI:10.1016/j.steroids.2017.10.001
日期:2017.12
Graphical abstract Figure. No Caption available. HighlightsTreatment of steroidsapogenins with TFA‐H2O2 led to pregnan‐3&bgr;,16&bgr;,20 triols.The obtained compound were characterized by their NMR spectra.X‐ray diffraction analysis corroborated the obtained structures. Abstract Treatment of steroidsapogenins with H2O2 in CF3COOH for 15 min followed by reflux in CH3OH/H2O afforded good yields of
Biomimetic Synthesis of 5,6-dihydro-glaucogenin C: Construction of the Disecopregnane Skeleton by Iron(II)-Promoted Fragmentation of an α-Alkoxy Hydroperoxide
作者:Jinghan Gui、Dahai Wang、Weisheng Tian
DOI:10.1002/anie.201101893
日期:2011.7.25
A skeleton key: A biomimeticsynthesis of the title natural product was completed in 19 steps and 6.4 % overall yield. Iron(II)‐promoted fragmentation of α‐alkoxy hydroperoxide and subsequent trapping of the resulting tertiary carbon radical by iodide enabled the highly efficient construction of the challenging 13,14:14,15‐disecopregnaneskeleton (see scheme; TBDPS=tert‐butyldiphenylsilyl).
Semisynthesis of Azedarachol from Pregnanetriol, a Degradative Product of Tigogenin
作者:Dongshan Zhang、Yong Shi、Weisheng Tian
DOI:10.1002/cjoc.201500231
日期:2015.6
We report the first semisynthesis of the natural insect antifeedant azedarachol. The synthesis features the employment of pregnanetriol, a degradative product of the resource natural product tigogenin, as the starting material, the symbiotic reaction involving the mutually‐promoting elimination of toluene‐sulfonate and deprotection of acetonide, and the controllable reactions between the C16‐OH and