The first enantioselective synthesis of (+)-trans-195A is described. The structure has been constructed by ring-rearrangement metathesis (RRM) and zirconium-mediated Negishi-coupling, used for the first time to prepare 6,6-membered heterocycles, as key steps. By comparison of the synthesized material with the isolated natural product, the absolute configuration of natural trans-195A was determined to be (2R,4aS,5R,8aS)-(-).
Diastereoselective Synthesis of 2,5-Disubstituted Decahydroquinolines via Ring-Rearrangement Metathesis and Zirconium-Mediated Cyclization
作者:Siegfried Blechert、Jürgen Neidhöfer
DOI:10.1055/s-2004-834904
日期:——
zirconium-mediated cyclization of unsaturated a,a'-disubstituted piperidines II is described. The required piperidines could be obtained from secondary sulfonamides III via ruthenium-catalyzed ring-rearrangementmetathesis (RRM) in high yields. Racemic trans-195A and 2-epi-trans-195A were synthesized in 8 steps starting with butyraldehyde and cyclohex-2-enol.
描述了通过锆介导的不饱和 a,a'-二取代哌啶 II 环化对 2,5-取代十氢喹啉的非对映选择性方法。所需的哌啶可以通过钌催化的环重排复分解 (RRM) 从仲磺酰胺 III 中以高收率获得。外消旋 trans-195A 和 2-epi-trans-195A 从丁醛和 cyclohex-2-enol 开始分 8 步合成。
2-Cyano Δ3 piperideines VIII : Biomimetic approach to the synthesis of the decahydroquinoline ring system of poison-dart frog toxins
A biomimeticapproach towards the synthesis of pumiliotoxin C has been developed. The key transformation of enamine equivalent 8 to 9 was catalyzed by contact with alumina. Cyclized intermediate 9 was then reduced stereospecifically to the trans decahydroquinoline 11 or stereoselectively to the cis compound 12.