The synthesis of 8a-methoxy-2H,6H-chromen-6-ones and corresponding 2H-chromenes by a unique process utilising phenolic oxidation

Article abstract of DOI:10.1016/S0040-4020(97)00008-2

(Z)-1-Hydroxy-3-(3'-hydroxyphenyl)prop-2-enes undergo phenolic oxidation by phenyliodonium diacetate (PIDA) in methanol to give 8a-methoxy-2H,6H-dihydrochromen-6-ones. These are reduced by DIBAL-H to 2-substituted-Δ^3,4-chromenes the overall process being a unique heterocyclic synthesis in which the heteroatom is not initially attached to a benzene ring, but is introduced from a side chain. Parallel oxidations using cis-1-hydroxy-3-(3'-hydroxyphenyl)prop-2,3-oxiranes have also been achieved despite the presence of the sensitive oxirane ring.