In connection with elucidating the role of L-leucine as a neuroactLive substance, the authors prepared 2-morpholinones by a ring closure from carboxyl group and amino group of L-leucine with alkylene oxide. These compounds were tested as to the pestitidal activity. Only 2-cyclohexylamino-1-phenyl-ethanol had the activity against adults of Tetranychus cinabarius.