Enantioselective total synthesis of (−)-strychnine: development of a highly practical catalytic asymmetric carbon–carbon bond formation and domino cyclization
作者:Takashi Ohshima、Youjun Xu、Ryo Takita、Masakatsu Shibasaki
DOI:10.1016/j.tet.2004.06.141
日期:2004.10
An enantioselective total synthesis of (−)-strychnine was accomplished through the use of the highly practical catalytic asymmetric Michael reaction (0.1 mol% of (R)-ALB, greater than kilogram scale, without chromatography, 91% yield and >99% ee), and a domino cyclization that simultaneously constructed the B- and D- rings of strychnine (>77% yield). Newly-developed reaction conditions for thionium
通过使用高度实用的催化不对称迈克尔反应(0.1 mol%的(R)-ALB,大于千克规模,无需色谱法,产率为91%,ee≥99 %),完成了对-(-)-士丁宁的对映选择性全合成。)和多米诺环化反应,同时构建了士的宁的B环和D环(收率> 77%)。硫鎓离子环化的新开发的反应条件,在路易斯酸存在下防止亚胺部分的NaBH 3 CN还原以防止开环反应以及在环外烯烃存在下硫醚的化学选择性还原(脱硫)至关重要完成合成。所描述的化学方法为合成更高级的马钱子碱生物碱铺平了道路。