Intramolecular Photocycloaddition of 3-(3-Butenyl)cyclohex-2-enone and 3-(2-Propenoxy)cyclohex-2-enone in Zeolites

The effects of zeolites on the intramolecular [2+2] photocycloadditions of 3-(3-butenyl)cyclohex-2-enone ( 1a) and 3-(2-propenoxy)cyclohex-2-enone (1b) were investigated. When 1a adsorbed in cation-exchanged zeolites X and Y was irradiated through a Pyrex filter, the products from the 1,6-ring closure biradical increased compared to the results from the photoreaction in homogeneous solutions. In the intramolecular 1,5-ring closure photocycloaddition of 1a and 1b, the products from the cis-fused intermediates increased in zeolites X and Y. The regiochemical and stereochemical outcomes of the photocycloadditions in the zeolites were interpreted by the binding of the guest molecules with the cations in the supercages.