Partially fluorinated heterocyclic compounds. Part IX. The syntheses of 4,5,6,7-tetrafluorobenzo[b]furan and 4,5,6,7-tetrafluoro-2-phenylbenzo[b]furan by a new cyclisation reaction, and the attempted syntheses of related compounds by conventional methods

Abstract

4,5,6,7-Tetrafluorobenzo[b]furan and 4,5,6,7-tetrafluoro-2-phenylbenzo[b]furan have been prepared by the sodium hydride-induced cyclisation of (pentafluorophenyl)acetaldehyde and 2-(pentafluorophenyl) acetophenone, respectively. Attempted cyclisation of ethyl (2-ethoxycarbonyl-3,4,5,6-tetrafluorophenoxy) fluoroacetate and of 2′,3′,4′,5′,6′-pentafluoro-2-hydroxyacetophenone both failed.