Kutznerides 1-4, depsipeptides from the actinomycete Kutzneria sp. 744 inhabiting mycorrhizal roots of Picea abies seedlings
Bioassay-guided fractionation of culture supernatants of the actinomycete Kutzneria sp. 744 resulted in the isolation of four new depsipeptides (1-4). Structure analysis revealed the general structure: cyclo[2-(1-methylcyclopropyl) -D-glycine-(2S,3aR,8aS)
L-threo- and L-erythro-3-Fluoroglutamic Acids. Synthesis by Fluorodehydroxylation and Enzymatic Resolution.
threo- and erythro-3-fluoroglutamic acids were prepared by fluorodehydroxylation of N-acetyl-3-hydroxyglutamic acids according to Kollonitsch.Following ion exchange column separation of the diastereoisomers, enzymatic deacylation by acylase I afforded optically pure L-isomers of the 3-fluoroglutamic acid.Assignment of structure was achieved by correlation with cis- and trans-3-fluoropyroglutamic acids.The results indicate predominant inversion of configuration during the fluorodehydroxylation reaction.