A common conformation for five cyclic tetrapeptides

Abstract

Cyclo-(Sar₃–N-MeAla), cyclo-(Sar₃–Ala), cyclo-(Sar₃–Gly), and cyclo-(Sar–Gly–Sar–Gly) have been synthesized; the similarity of their low-temperature n.m.r. spectra with that of cyclo-(Sar₄) suggests that all have the same ring conformation.