Enantioselective Synthesis of 4-Isoxazolines by 1,3-Dipolar Cycloadditions of Nitrones to Alkynals Catalyzed by Fluorodiphenylmethylpyrrolidines
作者:José Alemán、Alberto Fraile、Leyre Marzo、José Luis García Ruano、Cristina Izquierdo、Sergio Díaz-Tendero
DOI:10.1002/adsc.201200033
日期:2012.6.18
The first organocatalytic enantioselective 1,3‐dipolar reaction between nitrones and alkynals catalyzed by (S)‐2‐(fluorodiphenylmethyl)pyrrolidine to give 4‐isoxazolines (2,3‐dihydroisoxazoles) with high enantiomeric excess, excellent yields and low catalyst loading (1–5 mol%) is presented. The catalytic loading could be reduced to 1 mol% with only slight increases in reaction times.
(S)-2-(氟二苯基甲基)吡咯烷催化的硝酮与炔烃之间的第一个有机催化对映选择性1,3-偶极反应,得到对映体过量高,产率高,催化剂负载低的4-异恶唑啉(2,3-二氢异恶唑)( 1-5%(摩尔)。催化负荷可以降低到1摩尔%,而反应时间仅稍微增加。