Iron-Catalyzed Oxidative C-C and N-N Coupling of Diarylamines and Synthesis of Spiroacridines

We describe iron-catalyzed intermolecular oxidative coupling reactions of diarylamines to form substituted 2,2'-bis( arylamino) biaryl compounds, tetraarylhydrazines, and 5,6-dihydrobenzo[c]cinnolines with the same hexadecafluorinated iron-phthalocyanine catalyst. The mild formation of C-C or N-N bonds was controlled by the use of acidic or basic additives. In contrast to most iron-catalyzed dehydrogenative coupling reactions, ambient air could be used as the sole oxidant. Moreover, iron(III) chloride hexahydrate promoted a one-pot coupling and subsequent intramolecular dearomative coupling to give 10H-spiro[acridine-9,1'-cyclohexa-2', 5'-dien- 4'-ones].