Chimeric cyclodepsipeptides as mimetics for the anthelmintic PF1022A

In the anthelmintic cyclooctadepsipeptide PF1022A (1) didepsipeptide units have been exchanged for the β-turn mimetics (d)-Pro-(l)-Pro and BTD (7) in order to elucidate the functional role of the depsipeptide backbone. Compounds 12 and 14 are the first PF1022A analogues in which a substantial part of the PF1022A backbone has been replaced with an improvement of anthelmintical activity. Preliminary structure–activity relationships suggest a symmetric conformation to be the biological active one.