Mulberry Diels- Alder adducts: Synthesis of chalcomoracin and mulberrofuran C methyl ethers

Abstract

(Figure Presented) The synthesis of each of the heptamethyl ethers of the mulberry Diels-Alder adducts chalcomoracin (1) and mulberrofuran J (2) is described. The key steps In each approach involved a biomimetic intermolecular [4+2]-cycloaddition between a dehydroprenylphenol diene derived from an Isoprenoid-substituted phenolic compound and an αβ-unsaturated alkene of a chalcone as the dienophlle. Critical to the success of the Diels-Alder reaction was the presence of the free phenol in the 2′-hydroxychalcone. © 2010 American Chemical Society.