Scalable Total Syntheses of Some Natural and Unnatural Lamellarins: Application of a One-Pot Domino Process for Regioselective Access to the Central 1,2,4-Trisubstituted Pyrrole Core
Short and scalable total syntheses of lamellarinGtrimethylether, lamellarin D trimethylether, lamellarin H, lamellarin η, dihydrolamellarin η, and lamellarin U have been realized in four to six linear steps with an overall yield of ≤22%. Highlights of the synthesis include single-step access to the central 1,2,4-trisubstituted pyrrole core in a highly regioselective manner via a one-pot [3+2]
作者:Fei-Yu Chen、Li Xiang、Gu Zhan、Hong Liu、Bin Kang、Shu-Cang Zhang、Cheng Peng、Bo Han
DOI:10.1016/j.tetlet.2020.151806
日期:2020.4
The highly stereoselective synthesis of pyrrolidine-fused spirooxindole derivatives bearing a carbon-halogen bond and contiguous quaternary carbon stereocenters was achieved via a [3+2] cycloaddition reaction. This method provided facile access to a collection of enantiomerically pure spiro[pyrrolidin-3,2’-oxindoles] containing halogenated contiguous quaternary carbon stereocenters in good to high
通过[3 + 2]环加成反应实现了具有碳-卤素键和连续的季碳立体中心的吡咯烷稠合的螺并氧杂吲哚衍生物的高度立体选择性合成。该方法可轻松获得对映体纯的螺[吡咯烷-3,2'-羟吲哚]的集合,其中包含卤化连续的季碳立体中心,具有良好至高产率(48-84%)和出色的立体选择性(高达> 20:1 dr和> 99%ee)。可以通过亲核取代(S N 2)反应将含卤素的产物立体选择性地转化为硫化衍生物,这表明它们可以作为具有潜在生物活性的共价抑制剂的开发候选者。
Synthesis of Enantiopure 2-<i>C</i>-Glycosyl-3-nitrochromenes
作者:Raquel G. Soengas、Humberto Rodríguez-Solla、Artur M. S. Silva、Ricardo Llavona、Filipe A. Almeida Paz
DOI:10.1021/jo4021634
日期:2013.12.20
A novel methodology has been developed to obtain enantiopure 2-C-glycosyl-3-nitrochromenes. First, (Z)-1-bromo-1-nitroalkenes were prepared from the corresponding sugar aldehydes through a sodium iodide-catalyzed Henry reaction with bromonitromethane followed by elimination of the resulting 1-bromo-1-nitroalkan-2-ols. In the next step, reaction of the sugar-derived (Z)-1-bromo-1-nitroalkenes with o-hydroxybenzaldehydes afforded enantiopure (2S,3S,4S)-3-bromo-3,4-dihydro-4-hydroxy-3-nitro-2H-1-benzopyrans, which, upon SmI2-promoted beta-elimination, yielded chiral enantiopure 2-C-glycosyl-3-nitrochromenes.