Journal of Molecular Catalysis A-Chemical, Vol.357, 133-140, 2012
Varying the ratio of formic acid to triethylamine impacts on asymmetric transfer hydrogenation of ketones
Asymmetric transfer hydrogenation (ATH) is frequently carried out in the azeotropic mixture of formic acid (F) and triethylamine (T), where the FIT molar ratio is 2.5. This study shows that the F/T ratio affects both the reduction rate and enantioselectivity, with the optimum ratio being 0.2 ill the ATH of ketones with the Ru-TsDPEN catalyst. Under such conditions, a range of substrates have been reduced, affording high yields and good to excellent enantioselectivities. In comparison with the common azeotropic F-T system, the reduction is faster. This protocol improves both the classic azeotropic and the aqueous-formate system when using water-insoluble ketones. (C) 2012 Elsevier B.V. All rights reserved.