Disclosed are compounds of formula (I) or pharmaceutically acceptable non-toxic salts or pharmaceutically acceptable solvates thereof wherein: (II) represents (a), (b), (c) or (d) and W, X, Y, A, B, C, D, E are variables as described herein. These compounds are highly selective agonists or antagonists at NK3 receptors or prodrugs thereof. The novel tachykinin NK-3 receptor antagonists contained in this invention have potential utility in the treatment of a broad array of disorders and diseases of the central nervous system (CNS) and periphery in mammals in which activation of NK-3 receptors is of importance.