anti-Michael addition of (R)-(+)-1-phenylethylamine to methyl bis(trif
luoromethyl)acrylate (1b) leads to a 52:48 mixture of the diastereomer
ic adducts (S,R)- and (R,R)-3a. After addition of hydrochloric acid, t
he diastereomeric salt (S,R)-3b crystallizes in a pure form to give, u
pon 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].