This work describes the use of a 2,5,5-trisubstituted imidazoline as a
n amide bond replacement The replacement is incorporated into dipeptid
e derivatives of Phe, Trp, Lys and Nle and also into the CCK-4 analogu
e Trp-Nle-Asp-Phe-NH2 and the pentagastrin analogue Gly-Trp-Nle-Asp-Ph
e-NH2. The amide bond replacement is synthesised in enantiomerically a
nd diastereomerically pure form.