Cyano-activated fluoro displacement reactions in the synthesis of cyanophenoxazines and related compounds

Abstract

Cyano-activated fluoro displacement reactions between 2,3- and 3,4-difluorobenzonitriles and the nucleophiles catechol, 2-aminophenol, 2-aminobenzenethiol and benzene-1,2-dithiol either in DMF at 130 °C or in DMSO at rt, in the presence of potassium carbonate, lead to new substituted heterocycles or other species in high yield. Catechol at rt gives quantitative yields of cyanodibenzo[1,4]dioxines. 2-Aminophenol and 2-aminobenzenethiol at 130 °C give cyanophenoxazines and cyanophenothiazines, respectively, while at rt 2-aminophenol yields (aminophenoxy)cyanofluorobenzenes which can be converted into different cyanophenoxazines on heating in the presence or absence of base. The base-catalysed reactions involve a Smiles rearrangement. Benzene-1,2-dithiol yields cyanothianthrenes (130 °C) or a mixture of cyanothianthrene and bis(cyanofluorophenylsulfanyl)benzenes at rt.