Preussochromone Puzzle: Structural Revision of Preussochromones E and F by Total Synthesis
Marc Paul Beller1, Sergei Ivlev1, Ulrich Koert1
1Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35032 Marburg, Germany.
Abstract:
A stereoselective synthesis of the proposed and actual structures of the natural products preussochromones E and F is reported. The key step is a ring-closing metathesis to close the five-membered ring and install the trans configuration of the annulated five-six ring system. The analysis of the 3J NMR couplings of the isolated natural product with the synthesized compound revealed its real structure with a cis annulation, which could also be synthesized using an intramolecular aldol reaction of a vic-tricarbonyl compound.
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