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 (cinchonaalkaloidderivatives) themselves may be used as Lewis base catalysts, this new method may also be viewed as
Organocatalyzed enantioselective synthesis of 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles
作者:Sanjib Gogoi、Cong-Gui Zhao
DOI:10.1016/j.tetlet.2009.02.210
日期:2009.5
The first enantioselectivesynthesis of biologically active 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles has been achieved through a cinchona alkaloid-catalyzed tandem Michaeladdition and Thorpe-Zieglertype reaction between 2-pyrazolin-5-ones and benzylidenemalononitriles. The reaction may also be carried out in a three-component or a four-component fashion via the in situ formation of these two
通过金鸡纳生物碱催化的串联迈克尔加成和2-吡唑啉-5-酮与亚苄基丙二腈之间的Thorpe-Ziegler型反应,首次实现了生物活性6-氨基-5-氰基二氢吡喃并[2,3- c ]吡唑的对映选择性合成. 该反应也可以通过由简单且容易获得的起始材料原位形成这两种组分以三组分或四组分方式进行。以极好的收率获得了所需的产物,具有中等至极好的对映选择性(高达 >99% ee)。