Asymmetric Total Syntheses and Structure Elucidations of (+)-Eurotiumide F and (+)-Eurotiumide G

Asymmetric total syntheses of dihydropyran containing natural products, (+)-eurotiumide F and (+)-eurotiumide G have been described. These total syntheses revealed the absolute configuration of eurotiumide F and G, and confirmed the reported structure of eurotiumide F and revised the reported structure of eurotiumide G. Highlight of these syntheses is thermal rearrangement with 4-methoxyisochroman-1-one derivative having propargyl ether on phenolic ether under thermal condition to construct dihydropyran ring. X-Ray crystallographic analysis of (+)-eurotiumide G clarified the stereochemistry at the C1-position.