Asymmetric synthesis of crambescin A–C carboxylic acids and their inhibitory activity on voltage-gated sodium channels
作者:Atsuo Nakazaki、Yoshiki Nakane、Yuki Ishikawa、Mari Yotsu-Yamashita、Toshio Nishikawa
DOI:10.1039/c6ob00914j
日期:——
Synthesis of both enantiomers of crambescin B carboxylic acid is described. A cis-enyne starting material was epoxidized under the conditions of Katsuki asymmetric epoxidation to give 95% ee of the epoxide, which was transformed to crambescin B carboxylic acid via bromocation-triggered cascade cyclization as the key step. Enantiomerically pure crambescin A and C carboxylic acids were also synthesized
描述了克拉贝星B羧酸的两种对映异构体的合成。在胜木不对称环氧化条件下将顺式-烯炔原料进行环氧化,得到95%ee的环氧化物,通过溴化触发级联环化是关键步骤。还从级联反应的产物合成对映体纯的克拉贝星A和C羧酸。使用这些合成化合物对电压门控性钠离子通道(VGSC)抑制的结构活性关系(SAR)研究表明,克拉姆贝星B羧酸的天然对映异构体活性最高,与河豚毒素相当,而未烷基化的环胍盐结构则必不可少。羧酸根部分并不重要。克拉姆贝星A的绝对立体化学是通过将天然克拉姆贝星A衍生的甲基酯与本研究中合成的立体化学定义的克拉姆贝星A羧酸衍生的甲基酯进行比较来确定的。