(R)-3,5-Bis[(E)-benzylidene]-1-(1-phenylethyl)piperidin-4-one, 3,5-bis[(E)-4-chlorobenzylidene]-1-[(R)-1-phenylethyl]piperidin-4-one and 3,5-bis[(E)-2-chlorobenzylidene]-1-[(R)-1-phenylethyl]piperidin-4-one.