Synthesis of the Tetracyclic Framework of the Erythrina Alkaloids Using a [4 + 2]-Cycloaddition/Rh(I)-Catalyzed Cascade of 2-Imidofurans
作者:Albert Padwa、Qiu Wang
DOI:10.1021/jo061269p
日期:2006.9.1
undergo a rapid intramolecular [4 + 2]-cycloaddition to deliver oxabicyclo adducts in good to excellent yields. By using a Rh(I)-catalyzed ring opening of the resulting oxabicyclic adduct, it was possible to prepare several highly functionalized tetrahydro-1H-indol-2(3H)-one derivatives which were then used to prepare several erythrina alkaloids. By taking advantage of the Rh(I)-catalyzed reaction, it was
发现几种2-亚氨基取代的呋喃经历了快速的分子内[4 + 2]-环加成反应,从而以良好或极好的收率递送了氧杂双环加合物。通过使用得到的恶双环加合物的Rh(I)催化的开环,可以制备几种高度官能化的四氢-1 H-吲哚-2(3 H)-one衍生物,然后将其用于制备几种赤藓生物碱。通过利用Rh(I)催化的反应,可以转化叔丁基3-氧代-5-羰基甲氧基-10-氧代-2-氮杂三环[5.2.1.0 1,5通过与苯基硼酸反应,使[dec-8-ene-2-羧酸] dec-8-enelate开环成硼酸酯。用频哪醇/乙酸处理硼酸酯得到相应的二醇,该二醇用于成功合成外消旋3-脱甲氧基赤藓醇二酮。在这些研究过程中,尝试诱导关键内酰胺中间体的酸引发的Pictet Spengler环化反应时遇到了几种新颖的重排反应。所述IMDAF /铑(I) -催化的开环级联序列也适用于(±)-erysotramidine以及所述石蒜碱型生物碱的全合成(±)