Asymmetric Reductions in Ionic Liquids

In general, the catalyhc achvihes of the Rh catalysts in the ionic liquid-based solvent systems are largely dependent not only on the chiral ligands but also on the solvent system. Mostly ionic liquid/iPrOH biphasic solvent systems are 

COOMe NHAc Hz Rh(l)-(R,R)-Et-DuPhos ionic liquid/alcohol COOMe - A NHAc  

In contrast to air-sensitive chiral Rh-phosphine complexes, the chiral Ru complexes of BINAP or BINAP analogues were known to be more effectively 

However, the conversion and enantioselectivity were slowly decreased from the fifth run onwards (entries 21-25). Nevertheless, these results clearly demonstrated the effects of ionic tag on the catalyst recycling in ionic liquids. 

Moreover, it was found that the replacement of 16 with [Rh(COD)Cl]2 as the catalyst precursor resulted in a decreased catalytic performance in both [omim][B F4] and THF (entries 5-6). Based on these observations, it has been suggested that the hydrogenation process with rhodacarborane-based 16 may differ from that with [Rh(COD)Cl]2 in terms of its mechanistic pathways. The most efficient ionic 

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