Asymmetric Cascade Catalysis with Chiral Polyoxometalate-Based Frameworks: Sequential Direct Aldol and Epoxidation Reactions
作者:Qiuxia Han、Wenwen Li、Shugai Wang、Jiachen He、Wei Du、Mingxue Li
DOI:10.1002/cctc.201700160
日期:2017.5.23
applied in the conversion of aldehyde with ketone into value‐added chiral epoxy ketones in a one‐pot procedure. The chiral pyrrolidine organocatalysts interact with the carbonyl group of ketones throughout the reaction, which is beneficial for achieving compatibility between the reaction intermediates and synergy of the multiple catalytic cycles, thus driving the direct aldol/epoxidation cascade reaction
催化不对称级联反应越来越受到人们的关注,在这种反应中,底物通过精心设计的连续独立步骤由单个催化剂转移。通过将手性有机催化剂吡咯烷,氧化催化剂多金属氧酸盐和路易斯酸催化剂铜(II)合并到单个多孔配位网络(PCN)中,形成具有新型Kagomé晶格的两个对映体CuW-PYIs(PYI =吡咯烷-2-基咪唑)通过一锅法实现了将乙醛与酮转化为增值手性环氧酮的成功应用。在整个反应过程中,手性吡咯烷有机催化剂与酮的羰基相互作用,这有利于实现反应中间体之间的相容性和多个催化循环的协同作用,因此以有序和不对称的方式驱动直接的羟醛/环氧化级联反应。此外,在直接的羟醛/环氧化级联反应中很好地证明了“双中心催化”原理。