A Note on Intramolecular Photochemical Cycloaddition of N-substituted Dimethacrylimides

The intramolecular photochemical [2+ 2]-cycloaddition of N-substituted dimethacrylimides 1a and 1c , respectively, proceeds under conditions of direct irradiation (λ = 254 nm) as well as triplet photosensitization highly regioselectively yielding predominantly the «cross» bonding (head-to-tail) cycloadducts 3a and 3c , respectively, with a 3-azabicyclo [3.1.1]heptane ring system.