Operationally convenient asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid -: Part I:: Enantioselective biomimetic transamination of isopropyl 4,4,4-trifluoro-3-oxo-butanoate

DBU-catalyzed asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid via enantioselective biomimetic transamination of isopropyl 4,4,4-trifluoro-3-oxobutanoate with (R)- and (S)-phenylethylamine has been developed. The effect of the base concentration of the reaction rate and stereochemical outcome has been systematically studied. The key reaction step, DBU-catalyzed 1,3-proton shift transfer was found to be highly enantioselective (> 95% ee). However, due to some racemization of the intermediate Schiff base under the highly basic reaction conditions leads to the final product of lower enantiomeric purity. (c) 2006 Elsevier B.V. All rights reserved.