Aqueous asymmetric transfer hydrogenation using modular hydrophobic aminoalcohols

A series of new modular Ru/aminoalcohol systems were used as enantioselective catalysts in the asymmetric transfer hydrogenation reaction in both water and 2-propanol. The catalytic behavior exhibited in these two media follows different tendencies regarding the tunable ligand structure. While the bulkiness of the R1 group has a positive effect on the activity for reactions in 2-propanol, ligands with bulky R1 groups are generally less active in water. Additionally, cationic, anionic, and neutral surfactants do not improve the catalytic behavior in water.

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(1R,2R)-1-(Benzylamino)-3-methoxy-1-phenylpropan-2-olC17H21NO2Ee > 99.9%[α]D24=-466.3 (c 1.03, CHCl3)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)

(1R,2R)-1-(Biphenyl-4-ylmethylamino)-3-methoxy-1-phenylpropan-2-olC23H25NO2Ee > 99.9%[α]D24=-4.1 (c 0.96, CH2Cl2)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)

(1R,2R)-1-(Benzylamino)-1-phenyl-3-(trityloxy)propan-2-olC35H33NO2Ee > 99.9%[α]D22=-117.2 (c 0.67, CHCl3)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)

(1R,2R)-1-(Biphenyl-4-ylmethylamino)-1-phenyl-3-(trityloxy)propan-2-olC41H37NO2Ee > 99.9%[α]D22=+34.9 (c 1.09, CHCl3)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)

(1R,2R)-1-Phenyl-1-(4-trifuloromethyl)benzylamino-3-(trityloxy)propan-2-olC36H32F3NO2Ee > 99.9%[α]D23=-221.7 (c 0.99, CHCl3)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)

(1R,2R)-1-(4-Fluorobenzylamino)-1-phenyl-3-(trityloxy)propan-2-olC35H32FNO2Ee > 99.9%[α]D23=-193.7 (c 0.99, CHCl3)Source of chirality: Sharpless epoxidation of cinnamyl alcoholAbsolute configuration: (1R,2R)