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Recycling Chiral Imidazolidin‐4‐one Catalyst for Asymmetric Diels–Alder Reactions: Screening of Various Ionic Liquids
Author(s) -
Park Jin Kyoon,
Sreekanth Pentlavalli,
Kim B. Moon
Publication year - 2004
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200303167
Subject(s) - ionic liquid , chemistry , catalysis , yield (engineering) , diethyl ether , organic chemistry , extraction (chemistry) , ether , diels–alder reaction , medicinal chemistry , materials science , metallurgy
Various imidazolium ionic liquids such as [Bmim]PF 6 , [Bmim]SbF 6 , [Bmim]OTf and [Bmim]BF 4 were screened for recycling an organic catalyst [(5 S )‐5‐benzyl‐2,2,3‐trimethylimidazolidin‐4‐one ( 1 )] for asymmetric Diels–Alder reactions. Good yields and enantioselectivies (up to 85% yield and 93% ee) were obtained from reactions in [Bmim]PF 6 or [Bmim]SbF 6 . However, reactions in [Bmim]OTf or [Bmim]BF 4 gave racemic products in low yields. Isolation of the products by simple extraction using diethyl ether allowed recycling of the ionic liquid containing the immobilized catalyst in subsequent reactions without significant decrease of yields and enantioselectivities.