我们介绍了通过sa碘化analogue介导的γ-萘基取代的1,3-二酮的分子内酮基-芳基偶联反应合成新的类固醇类似物。从以前的使用γ-萘基单酮进行的实验中,可以预料到B / C / D环具有“非天然”顺式/顺式环化的高立体选择性。出乎意料的是,我们观察到两个具有顺式和反式的非对映异构体的形成。四环骨架的稠环B和C。证明非对映选择性强烈依赖于反应中所用质子源的量。讨论了这种意外行为的基本原理。此外,我们观察到了平滑的氯化铝诱导的γ-萘基取代的1,3-二酮之一的环化作用,提供了马来烯碱前体。另一种环化产物通过Grob片段化转化为环烷化环壬烷衍生物。
Pentacyclic Compounds by Samarium Diiodide‐Induced Cascade Cyclizations of Naphthyl‐Substituted 1,3‐Diones
摘要:
AbstractTreatment of naphthyl‐substituted cyclopentane‐1,3‐diones with the samarium diiodide‐ hexamethylphosphoramide (HMPA) complex in the presence of tert‐butyl alcohol provided the expected tetracyclic diols with steroid‐like structures. Surprisingly, reactions without the proton source led to the efficient formation of a new pentacyclic diol. In this case the toxic additive HMPA could be substituted by a combination of lithium bromide (in situ generation of samarium dibromide) and N,N‐dimethylimidazolidone. The styrene‐like alkene moiety of this product was used to prepare an ensemble of highly substituted pentacyclic steroid‐like compounds.
Pentacyclic Compounds by Samarium Diiodide‐Induced Cascade Cyclizations of Naphthyl‐Substituted 1,3‐Diones
作者:Ulrike K. Wefelscheid、Hans‐Ulrich Reissig
DOI:10.1002/adsc.200700283
日期:2008.1.4
AbstractTreatment of naphthyl‐substituted cyclopentane‐1,3‐diones with the samarium diiodide‐ hexamethylphosphoramide (HMPA) complex in the presence of tert‐butyl alcohol provided the expected tetracyclic diols with steroid‐like structures. Surprisingly, reactions without the proton source led to the efficient formation of a new pentacyclic diol. In this case the toxic additive HMPA could be substituted by a combination of lithium bromide (in situ generation of samarium dibromide) and N,N‐dimethylimidazolidone. The styrene‐like alkene moiety of this product was used to prepare an ensemble of highly substituted pentacyclic steroid‐like compounds.
Synthesis of new steroid analogues by samarium diiodide induced cyclisations of γ-naphthyl 1,3-diones
作者:Ulrike K. Wefelscheid、Hans-Ulrich Reissig
DOI:10.1016/j.tetasy.2010.04.036
日期:2010.6
rings B and C of the tetracyclic skeleton. The diastereoselectivity proved to be strongly dependent on the amount of the proton source employed in the reaction. A rationale for this unexpected behaviour is discussed. In addition, we observed a smooth aluminium chlorideinduced cyclisation of one of the γ-naphthyl-substituted 1,3-diones to furnish an equilenine precursor. Another cyclisation product
我们介绍了通过sa碘化analogue介导的γ-萘基取代的1,3-二酮的分子内酮基-芳基偶联反应合成新的类固醇类似物。从以前的使用γ-萘基单酮进行的实验中,可以预料到B / C / D环具有“非天然”顺式/顺式环化的高立体选择性。出乎意料的是,我们观察到两个具有顺式和反式的非对映异构体的形成。四环骨架的稠环B和C。证明非对映选择性强烈依赖于反应中所用质子源的量。讨论了这种意外行为的基本原理。此外,我们观察到了平滑的氯化铝诱导的γ-萘基取代的1,3-二酮之一的环化作用,提供了马来烯碱前体。另一种环化产物通过Grob片段化转化为环烷化环壬烷衍生物。