One of the enantiomers of 5,5-dimethylmorpholinyl-2-acetic acid is obs
erved to be a GABA(B) receptor antagonist. The absolute configuration
of the inactive enantiomer is found to be the R configuration. The mor
pholine ring adopts a chair conformation with the acetic acid moiety i
n an equatorial position. In the crystal packing, hydrogen bonds are o
bserved between the ammonium group and the chloride ions.