Synthesis of Dixanthones and Poly(dixanthone)s by Cyclization of 2-Aryloxybenzonitriles in Trifluoromethanesulfonic Acid
journal contributionposted on 06.07.2001, 00:00 authored by Howard M. Colquhoun, David F. Lewis, David J. Williams
Condensation of 2-fluorobenzonitriles with phenoxides affords 2-aryloxybenzonitriles that cyclize cleanly in trifluoromethanesulfonic acid at room temperature to give xanthone-iminium triflates. The CN bond in these compounds is remarkably resistant to hydrolysis, but prolonged reaction with strong aqueous acid under vigorous conditions affords xanthones in good yield. The synthesis is exemplified for a novel series of polynuclear dixanthones and for a high molar mass polyxanthone derived from the previously unreported monomer 3,3‘-difluoro-4,4‘-biphenyldicarbonitrile.