A series of N,N'-diacylpiperazine-2-carboxamides are shown to be antag
onists of the NK-1 Substance P) receptor. Elaboration of the C2 sidech
ain with aminoalkyl groups leads to two series of potent antagonists,
one containing simple dialkylamino groups and the second featuring 2-m
ethoxybenzylamino derivatives with divergent SARs with respect to subs
titution at the C2 amide bond.