Mechanism and Origin of Stereoselectivity in Chiral Phosphoric Acid‐Catalyzed Aldol‐Type Reactions of Azlactones with Vinyl Ethers
作者:Kyohei Kanomata、Yuki Nagasawa、Yukihiro Shibata、Masahiro Yamanaka、Fuyuki Egawa、Jun Kikuchi、Masahiro Terada
DOI:10.1002/chem.201905296
日期:2020.3.12
The precise mechanism of the chiral phosphoric acid‐catalyzed aldol‐type reaction of azlactones with vinyl ethers was investigated. DFT calculations suggested that the reaction proceeds through a Conia‐ene‐type transition state consisting of the vinyl ether and the enol tautomer of the azlactone, in which the catalyst protonates the nitrogen atom of the azlactone to promote enol tautomerization. In
研究了手性磷酸催化氮杂内酯与乙烯基醚的醛醇缩合反应的精确机理。DFT计算表明该反应通过由乙烯基醚和and内酯的烯醇互变异构体组成的Conia-ene型过渡态进行,其中催化剂使ates内酯的氮原子质子化,从而促进烯醇互变异构化。另外,催化剂的磷酰氧与乙烯基醚的乙烯基质子相互作用。有利的过渡结构具有配位氢键。但是,这些氢键不参与键的重组顺序,因此催化剂起着结合底物的模板的作用。从理论研究和实验支持的结果来看,