Phenyllactic acids are important constituents of depsipeptides, which are a large class of natural products expressing a wide range of biological activities. Despite there being several methods for the enantioselective synthesis of α-hydroxy acids, almost no studies are available addressing the substrate selectivity of transition-metal and enzyme-catalyzed methods for the preparation of substituted phenyllactic or more general aryllactic acids. We report herein comparative results for Rh-DiPAMP (DiPAMP = 1,2-ethandiylbis[(o-methoxyphenyl)phenylphosphane]) and lactate dehydrogenase catalyzed enantioselective reductions of several 3-aryl-2-oxopropanoic acids.

Cyclodepsipeptides of the enniation, PF1022 and verticilide families represent a diverse class of highly interesting natural products with respect to their manifold biological activities. However, until now, no practicable solid-phase syntheses of these compounds have been accomplished, probably due to the problematic combination of N-methyl amino acids and hydroxycarboxylic acids. We report herein an efficient synthesis of the anthelmintic PF1022A and its commercial analogue emodepside on Kaiser and Wang resins. Our protocol provides the basis for the solid-phase synthesis of cyclodepsipeptide libraries with a high probability of anthelmintic, antibacterial or insecticidal activity.