meta-Photocycloaddition of trans-1,2-dichloroethene to the benzene ring: directed cyclopropane ring formation in the tricyclo[3.3.0.02,8]oct-3-ene skeleton

Abstract

1,2-trans-Dichloroethene undergoes meta-photocycloaddition to benzonitrile, the toluonitriles, benzene, phenol, the cresols, fluorobenzene, chlorobenzene, trifluoromethylbenzene, and m-trifluoromethylbenzonitrile. The arene substituents selectively direct the positions of ethene attack, but in all cases the formation of the cyclopropane ring in the tricyclo[3.3.0.0^2,8]oct-3-ene skeleton is specifically controlled by the ethenyl chlorine to give exclusively the 6-exo-7-endo-dichloro adduct isomer.