A new catalytic mode of the modularly designed organocatalysts (MDOs): enantioselective synthesis of dihydropyrano[2,3-c]pyrazoles
作者:Savitha Muramulla、Cong-Gui Zhao
DOI:10.1016/j.tetlet.2011.05.092
日期:2011.7
MDOs are now used as a Lewis base in this base-catalyzed reaction. Since there are more reactions catalyzed by Lewis bases than by the enamine mechanism, this finding greatly expands the scope of the MDOs in organic reactions. On the other hand, because the stereocontrolling modules (cinchona alkaloid derivatives) themselves may be used as Lewis base catalysts, this new method may also be viewed as
利用模块化设计的有机催化剂(MDO)研究了3-甲基-2-吡唑啉-5-酮和苄基亚甲基腈之间的对映选择性串联迈克尔加成环化反应,生成6-氨基-5-氰基二氢吡喃[2,3- c吡唑类化合物的收率高,对映选择性中等至良好。最重要的是,建立了MDO的新催化模式。现在,MDO的反应中心模块(氨基酸)不再用作亲核试剂来形成烯胺中间体,而是在该碱催化的反应中用作路易斯碱。由于路易斯碱催化的反应多于烯胺机制,因此这一发现大大扩展了有机反应中MDO的范围。另一方面,因为立体控制模块(金鸡纳生物碱衍生物)本身可以用作路易斯碱催化剂,所以这种新方法也可以看作是修饰金鸡纳生物碱催化剂反应中心的快速方法。