Erik Fuglseth, E. Sundby, B. Hoff
Jun 1, 2009
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0
Influential Citations
22
Citations
Journal
Journal of Fluorine Chemistry
Abstract
Abstract The first examples of asymmetric transfer hydrogenation of α-fluoroacetophenones are reported. Eight para-substituted α-fluoroacetophenones have been reduced using four catalytic systems constructed of [RuCl2(p-cymene)2]2 or [RuCl2(mesitylene)2]2 in combinations with each of the ligands (1R,2R)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine ((R,R)-TsDPEN) and (1R,2R)-N-(p-toluenesulfonyl)-1,2-cyclohexanediamine ((R,R)-TsCYDN). All reactions were performed in both water and formic acid/triethylamine. The highest enantioselectivity was obtained using the (R,R)-TsDPEN ligand in a formic acid/triethylamine mixture, giving the (S)-1-aryl-2-fluoroethanols in high to moderate enantiomeric excess (97.5–84.5%). For this solvent system the presence of electron withdrawing groups in the para position reduced the enantioselectivity. Reactions performed in water generally gave lower enantioselectivity and reaction rate, although RuCl(mesitylene)-(R,R)-TsDPEN yielded the product alcohols with enantiomeric excess in the range of 95.5–76.5%.