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Synthesis 1996; 1996(9): 1070-1072
DOI: 10.1055/s-1996-4347
short paper
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Synthesis of Chiral α,α-Difluoro-β-hydroxy Esters by Enantioselective Reformatsky Reaction

José M. Andrés, María A. Martínez, Rafael Pedrosa* , Alfonso Pérez-Encabo
  • *Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid. Doctor Mergelina s/n, E-47011-Valladolid, Spain, Fax +34(83)423013
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Publication Date:
31 December 2000 (online)

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The addition of the Reformatsky reagent generated from ethyl bromo-α,α-difluoroacetate to aldehydes, in the presence of chiral amino alcohols, yields α,α-difluoro-β-hydroxy esters with good enantiomeric excess (ee) for aromatic aldehydes or modest ee for aliphatic ones. (1S,2R)-Ephedrine derivatives are better chiral inductors than (1S,2R)-dibutylnorephedrine, whereas the enantiodifferentiation is also affected by the molar ratio of the reactants. The best results are obtained from a molar ratio aldehyde/Reformatsky reagent/amino alcohol: 1/4/1.

enantioselective Reformatsky reaction - α,α-difluoro-β-hydroxy esters - chiral ligands enantioselective synthesis - chiral 1,2-amino alcohols