A new series of 4-substituted pipecolic acid derivatives was prepared and incorporated into dipeptoids. The resulting products behave as moderately potent CCK-B antagonists but their constrained structure and its comparison with structurally related compounds yield valuable information about the conformational requirements for optimal recognition of the CCK-B receptor by antagonists.
[Rutjes, Floris P. J. T.; Veerman, Johan J. N.; Meester, Wim J. N.; Hiemstra, Henk; Schoemaker, Hans E. European Journal of Organic Chemistry, 1999 , # 5 p. 1127 - 1135]
