A series of piperazinone ring systems have been synthesised as a means of evaluating the effect of conformational restriction on high affinity non-peptide NK1, NK3 and CCK-B receptor ligands. The synthesis of the targeted heterocycles is described along with a discussion of their affinities for their respective receptor types.
[Nelson, Todd D.; Rosen, Jonathan D.; Brands, Karel M.J.; Craig, Bridgette; Huffman, Mark A.; McNamara, James M. Tetrahedron Letters, 2004 , vol. 45, # 48 p. 8917 - 8920]