作者:Abdul Hameed、Alexander J. Blake、Christopher J. Hayes
DOI:10.1021/jo801540q
日期:2008.10.17
A second generation formal synthesis of the alkaloid (-)-cephalotaxine has been achieved using an alkylidene carbene 1,5-CH insertion reaction to establish a key quaternary stereocenter. The carbene precursor was readily derived from L-proline, and the 1,5-CH insertion reaction was performed under Ohira's conditions using lithiotrimethylsilyldiazomethane (LTDM), which gave the desired spirocyclic product
使用亚烷基卡宾1,5-CH插入反应建立关键的季立体中心,已完成了第二代生物碱(-)-头孢他辛的正式合成。卡宾前体很容易衍生自L-脯氨酸,并且在1,5-CH插入反应是在Ohira条件下使用硫代三甲基甲硅烷基重氮甲烷(LTDM)进行的,从而以74%的收率获得了所需的螺环产物。然后将羟甲基氧化,然后脱羰(93%),并将该材料轻松转化为所需的Friedel-Crafts环化前体。然后将该物质暴露于SnCl4中即可得到所需的五环产物,该产物与Mori先前制备的五环产物相同,因此代表了(-)-头孢他辛的正式全合成。