AN EXAMPLE OF A NOVEL FORMATION OF AN OXEPIN

A novel formation of an oxepin, namely tetrafluoro-5,6-dihydrobenzo[b] naphth[2,1-f]oxepin (5), starting from pentafluoroacetophenone and 1-t etralone is described. Also, the same synthesis using 1-indanone affor ds a very different ring system namely tetrafluoro-5,11b-dihydro-7H-be nzo[c]fluoren-7-one (10). Both synthesis undergo an intramolecular nuc leophilic substitution of an ortho-fluorine. In one case, the oxygen d isplaces the fluorine to afford the oxepin 5 and the other a carbon is used as the nucleophile to give the polycyclic ring system 10.