Nuevo método para la arilación de aminas aromáticas con ácido 2-clorobenzoico y derivados asistido por ultrasonido en dimetilformamida como disolvente

Abstract

A new procedure for the anilines arylation with 2-chlorobenzoic acids using the Ullmann condensation
under non classical conditions using ultrasonic irradiation at room temperature was developed. Potassium carbonate
was used as base, copper powder as a catalyst and N,N-dimethylformamide as a solvent. Several 2-anilinobenzoic acid
derivatives were obtained in 30 min reaction time with good yields (79 - 93 %), been superior to those obtained using
classical heating in 2 h reaction time. The use of pyridine as ligand was studied in this kind of condensation in presence
of ultrasonic irradiation. These conditions permit to reduce the reaction time to 10 min . In order to demonstrate the
scope of the ultrasound-assisted method, several 2-chlorobenzoic acids and different anilines were used obtaining 90 - 98
% yield in presence of pyridine. The advantages of this procedure include available substrates, the use of the inexpensive
copper powder, short reaction times, high yields without taking any precautions to exclude moisture under mild conditions
and experimental ease. Using this procedure several 2-anilinobenzoic acid derivatives were synthesized and identified
using a combination of analytical spectroscopic techniques