Theoretical conformational analysis on Cyclo(prolyl‐phenylalanyl) peptides

Abstract
Empirical energy calculations on cyclo(L‐Pro‐L‐Phe) and cyclo(L‐Pro‐D‐Phe) indicate that different conformations are possible for each molecule. The theoretical results are compared to ir, nmr, and crystallographic data. The interdependence between diketopiperazine ring and side‐chain conformations is also discussed.