Part I. Dibenzcycloheptatrienes. Part 2. A New Molecular Rearrangement Effected by Aluminium Chloride

A: Dibenzcycloheptatrienes. 2:3-Dimethoxy-9-and -10-mefhylphenanthrenes were synthesised and, by expansion of the central ring in each, were converted into dihenzocycloheptatrienones. Thereby 13:14-dimethoxy-3:4-5:6-dihenzocyclohepta-1:3:5-triene was isolated and fully characterised hut the isomeric triene was less well defined and attempted interconversion of the two gave results which were not free of ambiguity. B: A New Molecular Rearrangement effected by Aluminium Chloride. It is shown that through being heated with aluminium chloride chromanone is rearranged to 7-hydroxyindanone and dihydrocoumarin to 4-hydroxyindanone. Further applications of this type of rearrangement are described and discussed. In particular it is employed to prepare 6-hydroxyperinaphthen-7-one, the corresponding 8:9-dihydride and 6-hydroxy-perinaphthen-9-one. A comparative study of these three compounds is made to evaluate the chemical effects which are associated with the strong hydrogen-bonding present in the first of them. An improved method for the synthesis of chromanones has been developed