Photochemical Transformations of 1,5-Cyclooctadiene

Photolyses are reported of 1,5-cyclooctadiene: (i) by sensitization with mercury (3P1) atoms in the vapor phase, (ii) by direct irradiation in solution in the presence of cuprous chloride, and (iii) by irradiation in solution in a complexed state with rhodium chloride. The products from i are a polymer, bicyclo[5.1.0]octene-3 and tricyclo[3.3.0.02,6]octane. The polymer is believed to arise from a primary process which gives rise to free radicals. The other two products which are isomeric to 1,5-cyclooctadiene seem to be formed by intramolecular processes, analogs of which may be found in the photochemistry of 1,5-hexadiene. Process ii gives tricyclooctane in 30% yield while process iii gives 1,3-cyclooctadiene, bicyclo[4.2.0]octene-7, and 1,4-cyclooctadiene. It has been deduced that in ii the cuprous chloride acts merely as a catalyst for the isomerization reaction. © 1964, American Chemical Society. All rights reserved.