The photochemistry of simple, alicyclic enones has been the subject of extensive study during the last decade, and this area is the subject of a recent review.2Investigation of the crossed-cycloaddition of cyclopentenone to a variety of alkenes was undertaken in our laboratory in connection with a program of synthesis of precursors for nonbenzenoid, aromatic systems. In a previous report3we described the photoaddition of cyclopentenone to cycloheptene, from which four products were identified.