Semisynthetic routes to PF1022H-A precursor for new derivatives of the anthelmintic cyclooctadepsipeptide PF1022A

The cyclooctadepsipeptide PF1022A and its semisynthetic, commercial analogue emodepside show excellent anthelmintic properties. Bis-hydroxy PF1022 (PF1022H), a minor fermentative side-product represents an interesting precursor for new PF1022 related anthelmintics. We report herein two complementary routes which allow a highly efficient conversion of PF1022A to a regioisomeric mixture consisting mainly of the bis-para isomer PF1022H and the meta-para analogue. (c) 2016 Elsevier Ltd. All rights reserved.