Efficient Synthesis of (S)-Methyl Hexafluorovalinate

Authors:
  • RKReinhart Keese
    Reinhart Keese
  • CHChristian Hinderling
    Christian Hinderling
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Abstract
anti-Michael addition of (R)-(+)-1-phenylethylamine to methyl bis(trifluoromethyl)acrylate (1b) leads to a 52:48 mixture of the diastereomeric adducts (S,R)- and (R,R)-3a. After addition of hydrochloric acid, the diastereomeric salt (S,R)-3b crystallizes in a pure form to give, upon hydrogenolysis, an enantiomerically pure hydrochloric adduct of (+)-methyl hexafluorovalinate [(S)-4] to which the (S)-configuration was assigned. Treatment of (R,R)-3a with BBr3 gave hexafluorovaline [(R)-5].