The formation of benzoxacin-3-ones via intramolecular Nicholas reactions and synthesis of 8-membered heliannuols.

ABSTRACT

The γ-carbonyl cations generated from propargyl ether-Co2(CO)6 complexes undergo intramolecular Nicholas reactions to give dehydrobenzoxacin-3-one-Co2(CO)6 complexes in good yields. Reductive decomplexation and subsequent manipulation allows the synthesis of (±)-heliannuol K methyl ether and the formal syntheses of (±)-heliannuol K, (±)-heliannuol A, and (-)-heliannuol L.