Synthesis of cyanodibenzo[1,4]dioxines and their derivatives by cyano-activated fluoro displacement reactions

Abstract

A new group of cyanodibenzo[1,4]dioxines have been synthesized by cyano-activated fluoro displacement reactions between cyanodifluorobenzenes and catechols in DMF at 130 °C in the presence of potassium carbonate. This route is exemplified by the synthesis of cyanodibenzo[1,4]dioxines from several substituted catechols. The reactions are virtually quantitative. Cyanodibenzo[1,4]dioxines were hydrolysed with potassium hydroxide in ethylene glycol or converted into amide derivatives to yield additional substituted dibenzo[1,4]dioxines. Cyanodibenzo[1,4]-dioxines are fluorescent and excitation and emission data are presented. Improved syntheses of 4,5-diphenylveratrole and 3,6-dimethylcatechol, the latter involving reduction of a phenolic Mannich base at atmospheric pressure, have been elaborated.