Synthesis of (+)-Canadensolide, (-)-Santolinolide A and (+)-Santolinolide B: The Imino-Claisen Reaction in Natural Product Synthesis
作者:Udo Nubbemeyer
DOI:10.1055/s-1993-26013
日期:——
The iminoketene-Claisen reaction serves as a key step in an efficient asymmetric synthesis of (+)-canadensolide, (+)-santolinolide B and (-)-santolinolide A: Starting from D-mannitol an optically active N-allylacetamide was generated which was rearranged to the corresponding diastereomeric nitrile. After cyclization two optically active 4,5-difunctionalized γ-butyrolactones with defined configuration at the chiral centers were obtained. The syn-4,5 disubstituted lactone was used for the synthesis of (2R,3S,4S)-(+)-canadensolide, the anti-4,5 difunctionalized lactone was employed in the synthesis of the (3R,4S,5S)-(+)-santolinolide B and the (3S,4S,5S)-(-)-santolinolide A.
亚氨基酮-克莱森反应是高效不对称合成(+)-卡那登内酯、(+)-山莨菪碱内酯 B 和(-)-山莨菪碱内酯 A 的关键步骤:从 D-甘露醇开始生成具有光学活性的 N-烯丙基乙酰胺,然后将其重新排列为相应的非对映腈。 环化后,得到了两个具有光学活性的 4,5-二官能化 δ³-丁内酯,其手性中心具有确定的构型。合成(2R,3S,4S)-(+)-加拿芬内酯时使用了同-4,5-二取代内酯,合成(3R,4S,5S)-(+)-山道年内酯 B 和(3S,4S,5S)-(-)-山道年内酯 A 时使用了反-4,5-二官能化内酯。