Highly constrained dipeptoid analogues containing a type II′ β-turn mimic as novel and selective CCK-A receptor ligands

Abstract Conformationally constrained dipeptoid analogues containing the type II′ β-turn mimic (2 S ,5 S ,11b R )-2-amino-3-oxohexahydroindolizino[8,7- b ]indole-5-carboxylate framework in place of the α-MeTrp residue, show high binding affinity and selectivity for CCK-A receptors, suggesting that a turn-like conformation could contribute to the bioactive conformation at this CCK receptor subtype.