Ultrasound promoted asymmetric transfer hydrogenation of ketones using Ru(II)arene/amino alcohol catalyst system

Asymmetric transfer hydrogenation of ketones using Ru(II)arene/amino alcohol catalyst system proceeds with significant rate enhancement by ultrasound promotion. Comparison of the silent reactions carried out at 25 °C with reactions under sonochemical activation at 25 °C clearly showed enhancement in catalytic activity by 5-10 times without significantly affecting the enantioselectivity

Catalytic asymmetric transfer hydrogenation of ketones using [Ru(p-cymene)Cl<SUB>2</SUB>]<SUB>2</SUB> with chiral amino alcohol ligands

Catalytic asymmetric transfer hydrogenation of aromatic alkyl ketones has been investigated using [Ru(p-cymene)Cl<SUB>2</SUB>]<SUB>2</SUB> and new derivatives of &#946;-amino alcohols synthesized from (S)-(-)-lactic acid and mandelic acid as ligands. Chiral secondary alcohols were obtained with good to excellent conversion (60-90%) and moderate to good enantioselectivities (40-86%)

Asymmetric Transfer Hydrogenation of Imines in Water by Varying the Ratio of Formic Acid to Triethylamine

Asymmetric transfer hydrogenation (ATH) of imines has been performed with variation in formic acid (F) and triethylamine (T) molar ratios in water. The F/T ratio is shown to affect both the reduction rate and enantioselectivity, with the optimum ratio being 1.1 in the ATH of imines with the Rh-(1<i>S</i>,2<i>S</i>)-TsDPEN catalyst. Use of methanol as a cosolvent enhanced reduction activity. A variety of imine substrates have been reduced, affording high yields (94–98%) and good to excellent enantioselectivities (89–98%). In comparison with the common azeotropic F–T system, the reduction with 1.1/1 F/T is faster