Kinetic resolution of 5-substituted cycloalkenones by peptidic amidophosphane-copper-catalyzed asymmetric conjugate addition of dialkylzinc
作者:Takahiro Soeta、Khalid Selim、Masami Kuriyama、Kiyoshi Tomioka
DOI:10.1016/j.tet.2007.03.032
日期:2007.7
Asymmetric conjugate alkylation reaction of racemic 5-substituted cyclohexenones with dialkylzinc reagents was catalyzed by 2–5 mol % of dipeptidic amidophosphane-Cu(MeCN)4BF4 in toluene at 0 °C for 20 min to recover enantioenriched starting 5-substituted cyclohexenones with 88–98% ee in 28–41% yield along with trans major 3-alkylated 5-substituted cyclohexanones with 81–90% ee in 53–60% yield. Complete
外消旋的5-取代的环己烯酮与二烷基锌试剂的不对称共轭烷基化反应是在甲苯中于0°C下通过2–5 mol%的二肽酰胺基膦-Cu(MeCN)4 BF 4催化20分钟,以回收对映体富集的起始5-取代的环己烯酮ee的产率为88-98%,ee的产率为28-41%,而反式三烷基化的5-取代的环己酮的ee产率为81-90%,产率为53-60%。由不对称催化反应的条件下与二乙基锌处理原料外消旋的5- TMS环己烯酮的完全消耗,得到的反式主要85:15混合物反式-和顺具有15%ee(对于反式)的-3-乙基-5-TMS-环己酮,其合计产率为83%,这表明环己烯酮的构象控制的烷基转移反应胜过手性催化剂控制的对面相分化。