Enantioselective hydrogenation of ethyl 4-chloro-3-oxobutyrate in solutions of organic salts with recycling of the catalyst Ru-BINAP

Abstract

Enantioselective hydrogenation of ethyl 4 chloro 3 oxobutyrate in ionic liquid systems containing tetraethylammonium bromide, 1 butyl 3 methylimidazolium hexafluorophosphate, or 1 butyl 3 methylimidazolium trifluoromethanesulfonate in the presence of the chiral cata lyst Ru BINAP ensures a high level of asymmetric induction after at least threefold recycling of the catalyst.Key words: enantioselective hydrogenation, ethyl 4 chloro 3 oxobutyrate, ethyl 4 chloro 3 hydroxybutyrate, chiral ruthenium complexes, (R) and (S) BINAP, ionic liquid, tetraethyl ammonium bromide, recycling of the catalyst.

Notes on the Asymmetric Hydrogenation of Methyl Acetoacetate in Neoteric Solvents

“…The primary intention of this work was to evaluate and compare (positive and negative) aspects of various arrangements of the (R)-methyl 3-hydroxybutyrate synthesis from achiral methyl acetoacetate by means of the stereoselective hydrogenation [11,12,14] with the chiral Ru-BINAP complex. These arrangements comprised the standard homogeneous experiment with methanol as a solvent, the mixed solvent system of methanol-IL or methanol-CO 2 and finally the methanol-CO 2 with additives -water and organic chlorides.…”

“…Recently many new alternatives have appeared such as the three-dimensional entrapment of the catalyst [8] (based on the electrostatic catalyst-polyelectrolyte attraction), utilisation of magnetite nanoparticles [9] or immobilization of the complex in thin films of ionic liquids deposited on silica beads [10]. Also various types of ionic liquids (IL) have been considered as reaction co-solvents for selective accommodation of the catalytic phase [11][12][13][14][15]. Due to their physical properties and variable phase behaviour separation of the catalyst from the reaction mixture is feasible.…”

“…Due to their physical properties and variable phase behaviour separation of the catalyst from the reaction mixture is feasible. Currently the most popular types of ILs used for such purposes are imidazolium cations combined either with hexafluorophosphate or tetrafluoroborate, and quaternary ammonium cations (such as n-alkyl-triethylammonium) combined with the bis(trifluoromethane sulfonyl) imide anion [14][15][16][17].…”

Hydrogenation in Ionic Liquids

“…The hydrogenation of ethyl 4-chloro-3-oxobutyrate to give ethyl 4-chloro-3-hydroxy butyrate ( Figure 30) was investigated by Starodubtseva et al [88] using a Ru-BINAP (25) catalyst in various IL systems. Fig.…”

Asymmetric hydrogenation of the CO bond with the recycling of an organometal catalyst deposited on a solid organic polyelectrolyte

“…Recently, a method of TMCC recycling by 'immobilization' in organic salt solutions including ionic liquids has attracted considerable attention. [7][8][9][10][11][12][13][14] Another promising approach to TMCC recycling is based on the use of ionic polymers, polyelectrolytes (PEs), as catalyst carriers. In particular, an efficient catalyst system for asymmetric aldol reaction between aldehydes and ketones based on L-proline supported on organic PE, poly(diallyldimethylammonium salt) 1, has been recently elaborated.…”