OZONOLYSIS OF ACENAPHTHYLENE AND 1-SUBSTITUTED ACENAPHTHYLENES

The ozonolysis of 1-methylacenaphthylene (lb) and acenaphthylene (1c) in carbon tetrachloride, acetonitrile, acetic acid, and trifluoroethanol revealed that the ozonide yield was much higher in reactions in protic solvents than in aprotic solvents. Such an assistance of the protic solvents on the ozonide formation was not observed in the case of the more bulky 1-phenylacenaphthylene (1a). In the ozonolysis of la-c in methanol, capture of the ozonolysis intermediate by the solvent occurs significantly, affording in each case the corresponding na-phthopyran derivative 3. The structure of the methanol-derived product obtained from acenaphthylene (lc) is revised from the structure 14 reported by Callighan to the methoxynaphthopyran 3c, based on NMR data and chemical transformations. The structure of the methanol-derived products 3a,b demonstrates that fragmentation of the primary ozonide obtained from 1-methyl-and 1-phenylacenaphthylene occurs such that the hydroperoxide resides on the more substituted carbon. These data are compared with those of the ozonolysis of pyrene (17). © 1990, American Chemical Society. All rights reserved.