Cinchona Alkaloid-Catalyzed Enantioselective Amination of α,β-Unsaturated Ketones: An Asymmetric Approach to Δ2-Pyrazolines
作者:Nathaniel R. Campbell、Bingfeng Sun、Ravi P. Singh、Li Deng
DOI:10.1002/adsc.201100447
日期:2011.11
interest due to their therapeutic properties and utility in the synthesis of 1,3-diamines, yet few asymmetric methods exist to prepare them. An unprecedented highly enantioselective organocatalytic synthesis of 2-pyrazolines was achieved through an asymmetric conjugate addition catalyzed by 9-epi-amino cinchona alkaloids followed by deprotection-cyclization, which furnished chiral 2-pyrazolines in 46-78%
Delta2-吡唑啉因其治疗特性和在1,3-二胺合成中的实用性而具有重要的医学和合成意义,但制备它们的不对称方法很少。通过9-表位氨基金鸡纳生物碱催化的不对称共轭加成反应,然后进行脱保护环化作用,实现了对2-吡唑啉的前所未有的高对映选择性有机催化合成,这提供了手性2-吡唑啉,产率为46-78%,ee为59-91% 。因此,这种双功能催化方法易于获得相当范围的旋光性3,5-二烷基2-吡唑啉。