Photochemical intramolecular [2 + 2] cycloaddition of 5-(1- and 2-naphthylmethyl)-3-phenylcyclopent-2-enones

Abstract

Photolysis of 5-(1- and 2-naphthylmethyl)-3-phenylcyclopent-2-enones affords [2 + 2] cycloaddtion products, the 7,8- and 5,6-benzo-fused 10-phenyltetracyclo[7.2.1.0^3,10.0^4,9]dodec-5- and -7-en-2-ones respectively, in a mixture with the starting enones; the photoproducts revert to the respective enones on acid treatment, or pyrolysis, and to the photostationary-state mixture on photolysis.