Photochemical Rearrangements of 6‐Methoxymethylbicyclo[4.4.0]Dec‐1‐En‐3‐One and 6‐Methoxymethylbicyclo[4.3.0]Non‐1‐En‐3‐One

The irradiation of the title compounds 6 and 12 in isooctane and benzene was investigated. The photochemical reactions took place sluggishly upon n→π * excitation (λ > 300 nm) in deoxygenated solutions but more rapidly in the presence of air; deconjugation to yield β,γ‐unsaturated ketones and lumiketone rearrangement were the main primary photochemical reactions. In contrast, intramolecular hydrogen abstraction by the C α ‐carbon was the main reaction upon π→ * excitation (λ = 254 nm).