Thermal and Photochemical Interconversion of Several l&Naphtho(CdHd) Hydrocarbons. Tests of the Woodward-Hoffmann Rules

The photochemical and thermal interconversions of both deuterated and nondeuterated pleiadiene ( l) , 1,8-naphthobicyclo[3.2.0] hepta-2,6-diene (2), and 1,8-naphthotricycl0[4.1.0.0~~~]heptene (3) are reported. All of these isomerizations may be preliminarily explained in terms of allowed and forbidden pathways. For several of the re-ported examples, however, a more complex interpretation is required by the experimental data. Even though there has been much work done on the high-er members of the pleiadiene family,2 there are only a few reports on the preparation and isomerizations of the parent molecule (la) and the isomeric molecules 2a and 3a.3 Litera-ture records the formation of pleiadiene (la) from 1,8-