Proline-catalysed asymmetric aldol reaction in the room temperature ionic liquid [bmim]PF₆

Abstract

Proline-catalysed asymmetric direct aldol reaction of different aromatic aldehydes with acetone and several other ketones in the room temperature ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate achieved good yields of aldolisation products with reasonable enantioselectivities, even when just 1-5% of proline was used as the catalyst; immobilisation of the catalyst in an ionic liquid phase offers simple product isolation and reuse of the catalytical system in subsequent reactions.

L-Proline as an efficient and reusable promoter for the synthesis of coumarins in ionic liquid

“…L-Proline in combination with ionic liquids has proved to be an efficient system for Knoevenagel condensation (Wang et al, 2006), direct asymmetric aldol reactions (Loh et al, 2002;Kotrusz et al, 2002;Gruttadauria et al, 2004;Salaheldin et al, 2004), cross-aldol reactions (Córdova, 2004), Michael additions (Kitazume et al, 2003;Hagiwara et al, 2004;Kotrusz et al, 2004;Rasalkar et al, 2005), α-aminations of aldehydes and ketones (Kotrusz et al, 2005), Ullmanntype reactions , as well as Mannich reactions (Chowdari et al, 2003). To the best of our knowledge, there is no attempt of the use of L-proline as a promoter in ionic liquid for the synthesis of coumarins.…”

L-Proline Catalyzed Michael Additions of Thiophenols to α,β-Unsaturated Compounds, Particularly α-Enones, in the Ionic Liquid [bmim]PF6

“…We [24] and Loh et al [25] have simultaneously described the excellent results observed for L-proline catalyzed aldol reactions in ionic liquids. We have also reported [26] L-proline catalyzed additions of carbonyl compounds to β-nitrostyrenes.…”

Asymmetric Reductive Amination of Carbonyl Compounds by Using<i> N,N,N</i>-Tributylpropanaminium Based Novel Chiral Ionic Liquid

“…Room temperature ionic liquids occupy a prominent place and are recognized as green solvents for organic synthesis [12,13] in view of their unique physical and chemical, non-toxic properties and the possibility of their recycling. Also ionic liquids have been used as an alternative reaction media for several reactions [14,15] including electrolytes for batteries [16]. Among the room temperature ionic liquids, chiral ionic liquids are known to be attractive and important for their potential applications to chiral recognition such as asymmetric synthesis and optical resolution of racemates [17].…”