Synthesis of dimeric spirostanols linked through a 1,4-dimethylidenebenzene moiety by double BF3·Et2O-catalyzed aldol condensation of steroid sapogenins and terephtalaldehyde
作者:Manuel A. Ramos-Enríquez、Lucie Rárová、Martín A. Iglesias-Arteaga
DOI:10.1016/j.steroids.2018.08.005
日期:2018.12
BF3·Et2O‐catalyzed double aldol condensation between acetylated steroidsapogenins and terephtalaldehyde led to acetylated dimeric spirostanols linked through a 1,4‐dimethylidenebenzene moiety in moderate to good yields. The E configurations of the introduced double bonds were corroborated by NOE experiments. Saponification of the dimeric steroids led to the corresponding dimeric spirostanols.
亮点乙酰化螺甾烷醇和对苯二醛缩合生成二聚类固醇。皂化得到相应的二聚螺甾烷醇。NOE 实验证实了 1,4-二亚甲基苯部分的 E 构型。获得的二聚体在大多数溶剂测试中显示出极低的溶解度。摘要 BF3·Et2O 催化乙酰化甾体皂苷元和对苯二醛之间的双羟醛缩合反应生成乙酰化二聚体螺甾醇,通过 1,4-二亚甲基苯部分以中等至良好的产率连接。NOE 实验证实了引入双键的 E 构型。二聚类固醇的皂化导致相应的二聚螺甾醇。
BF3·Et2O-induced stereoselective aldol reaction with benzaldehyde, and steroid sapogenins and its application to a convenient synthesis of dinorcholanic lactones
作者:Karen M. Ruíz-Pérez、Margarita Romero-Ávila、Verónica Tinajero-Delgado、Marcos Flores-Álamo、Martín A. Iglesias-Arteaga
DOI:10.1016/j.steroids.2012.02.016
日期:2012.6
Treatment of steroidsapogenins with benzaldehyde and BF(3)·Et(2)O cleanly produces E-23(23')-benzylidenspirostanes in good yields in a reaction pathway which consists on an aldol reaction followed by a dehydration step. The obtained E-23(23')-benzylidenspirostanes can be easily converted to dinorcholanic lactones by treatment with CrO(3) in acetic acid. The synthetic sequence to dinorcholanic lactones
Synthesis and radical scavenger properties of novel spirochromenes derived from steroid sapogenins
作者:Manuel A. Ramos-Enríquez、Omar N. Medina-Campos、José Pedraza-Chaverri、Martín A. Iglesias-Arteaga
DOI:10.1016/j.steroids.2015.03.013
日期:2015.6
condensation between steroid sapogenins and hydroxylated benzaldehydes afforded steroidal spirochromenes. Compounds that bear a phenolic hydroxyl group at position C-6', obtained by a reaction with 2,5-dihydroxybenzaldehyde, showed approximately 80% of maximal radical scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay at 288 nM. In contrast, the starting steroid sapogenins and
Efficient Protocol for Ring Opening of Spiroketals Using Trifluoroacetyl Trifluoromethanesulfonate (TFAT)<sup>1</sup>
作者:Jong Seok Lee、Philip L. Fuchs
DOI:10.1021/ol035284h
日期:2003.10.1
[reaction: see text] Ringopening of steroidal spiroketals under exceptionally mild conditions is smoothly achieved via reaction with trifluoroacetyl trifluoromethanesulfonate (TFAT). The new spiroketal ring-opening protocol provides omega-trifluoroacetyl vinyl ethers in good yield and avoids difficulties that attended previously employed vigorous reaction conditions.
Concurrent ring opening and halogenation of spiroketals
作者:Thomas G. LaCour、P.L. Fuchs
DOI:10.1016/s0040-4039(99)00827-8
日期:1999.6
Ringopening of various spiroketals with triphenylphosphine dihalides under neutral conditions produced ω-halo-enolethers in good to excellent yield. The method transformed even the very stable spiroketal of hecogenin acetate at temperatures below any previously reported for such isomerative opening.