4-Phenylbutyrylprolylpyrrolidine, an inhibitor of prolyl-endopeptidase, exi
sts in solution as an equilibrium of hans and cis prolyl rotamers. The equi
librium ratio and the exchange rate of the rotamers were measured in severa
l solvents. The conformational preferences of the flexible molecule were st
udied by MMR, based on proton-proton vicinal coupling constants, NOESY cros
s peak intensities and aromatic ring current shifts. Copyright (C) 1999 Joh
n Wiley & Sons, Ltd.