Anionic ring expansion reactions of oxabicyclo[4.2.1]heptenones. An efficient entry into the carbon framework of oxygenated cembranoids

Oxabicyclo[2.2.1]heptenones undergo 2-carbon ring expansion reactions when subjected to anionic condensations and Michael acceptors. They also undergo condensation, fragmentation, and elimination reactions in their anionic couplings with aldehydes. As an outgrowth of this interesting chemistry, we have been able to access the carbon skeleton of oxygenated cembranoids by subjecting bis-activated ene-yne 39 to the enolate from oxabicyclo[2.2.1]heptenone 1.