A homodienolate-enone addition

On treatment with sodium hydride, a mixture of ketone 1 and enone 4 gives a 48% yield of adduct 2, which contains two new carbon-carbon bonds. The rea ction very likely involves homodienolate 3, which may either undergo a Mich ael addition or a cycloaddition to enone 4 to give intermediate adduct 6 or 7, respectively. Adduct 6 may then undergo homo-Michael addition to give a dduct 7. Cyclopropane ring-opening of adduct 7 and protonation give the obs erved adduct 2.