BINAP/ruthenium combinations

Homogeneous asymmetric hydrogenation of ketones has a 40 year history. In particular, the BINAP-ruthenium/Bronsted acid combined catalyst and the BINAP-ruthenium/diamine ternary catalyst revolutionised the asymmetric hydrogenation of ketones in 1987 and in 1995, respectively. Although the complementary use of these two catalysts covers a wide range of ketonic substrates, there is still no universal catalyst for the asymmetric hydrogenation of ketones. Because the production of chiral secondary alcohols through... 

Catalysts for ketone hydrogenation continue to be developed but one of the best systems is still the BINAP-DPEN catalyst first reported by Ohkuma et al. in 1995. " In this system ruthenium is combined with both a chiral diphosphine and a chiral diamine, forming an octahedral complex which gives a high degree of enantioselectivity. This stereoselectivity is considered to be a result of the synergistic effect of the chiral diphosphine and diamine ligands. 

Immobilization on zeolites mentioned before has the obvious limitation that the small size of their pores restricts the reaction to small substrate molecules. This has been overcome by a combination of two developments (1) removing the need for necessarily using an organic solvent for the catalyst by replacing it with water-soluble chiral rhodium- or ruthenium-sulfonated-BINAP (see section on... 

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