The copper-promoted reaction of o-halogenodiarylazo-compounds with nucleophiles. Part 2. The copper-promoted reaction of o-bromodiarylazo-compounds with diesters of phosphorous acid. A novel method for the preparation of dialkyl arylphosphonates

Abstract

o-Bromodiarylazo-compounds react with diethyl phosphate, in the presence of copper(I) iodide and sodium acetate in ethanol, to give the corresponding o-diethylphosphonato-diarylazo-compounds in good yield. Reaction is facilitated by the presence of an o′-donor substituent in the o-bromodiarylazo-compound. When diethyl phosphite is replaced by diphenyl phosphite the product is again the diethyl phosphonate. The use of diphenyl phosphite in alcohols other than ethanol affords a facile, general method for the preparation of a range off dialkyl phosphonates since the product obtained is the phosphonate ester corresponding to the alcoholic solvent employed.