New Benzodioxepin Type Strobilurins from Basidiomycetes. Structural Revsion and Determination of the Absolute Configuration of Strobilurin D and Related #beta#-Methoxyacrylate Antibiotics

摘要

The new antiobilurins I(1) and K(19) are,3,4-dihydro-2H-benzo[b][1,4]dioxipin derivatives. Their structure and stereochemistry was determined by degradation to aldehyde 3.Both enantiomers of 3 were synthesised and the absoluted configurations assigned by the high-field ~1H NMR variant of Mosher's method.(S)-3 is identical with the compounds derived from the natural products. In the course of these investigations the epoxide structures 15,16 and 17 previously assigned to strobiluin D, hydroxystrobilurin D and 9-methoxystrobilurin K have to be changed in 18,21 and 20,respectively. All these compounds possess the same benzodioxepin core structure and (S)-configuration as strobilurin I(1).