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 w as irradiated through a Pyrex filter, the products from the 1,6-ring closur e biradical increased compared to the results from the photoreaction in hom ogeneous solutions. In the intramolecular 1,5-ring closure photocycloadditi on of 1a and 1b, the products from the cis-fused intermediates increased in zeolites X and Y. The regiochemical and stereochemical outcomes of the pho tocycloadditions in the zeolites were interpreted by the binding of the gue st molecules with the cations in the supercages.