Synthetic Photochemistry. LXII. The Photoaddition of 4-Methyl-2-oxo-γ-valerolactone to Cycloalkenes

Photocycloaddition of 4-methyl-2-oxo-γ-valerolactone to cycloalkenes gave [2+2] cycloadducts, together with the ene reaction products. The stereostructures of photoproducts were identified by detailed NMR spectral analyses including NOE experiments. The photocycloadducts were convertible to (2-alkenylcycloalkyl)glyoxalic acids.