Synthesis of 1,5-Benzodiazepines with Unusual Substitution Pattern from Chalcones Under Solvent-Free Microwave Irradiation Conditions

Abstract

1,5-Benzodiazepines have been synthesized from the corresponding 2′-hydroxychalcones [1-(2-hydroxyphenyl)-3-aryl-2-propen-1-ones] and o-phenylenediamine, both in methanol, under reflux and under solvent-free microwave irradiation conditions on alumina. The latter method proved to be advantageous.

Keywords:

• Alumina
• benzodiazepine
• chalcone
• microwave irradiation
• solvent-free synthesis

ACKNOWLEDGMENTS

This work was supported by Fondecyt through Grant 1080147, awarded to C. A. E. O. D. T. is grateful to Universidad Andres Bello (UNAB) for a graduate fellowship. We are also grateful to Dr. Álvaro Cañete M. and to MECESUP UCH0116, the “Red Nacional de Doctorado en Química,” for the peak matching experiments.

Notes

^a Yields were determined by weighing the final product after column chromatography and recrystallization.

^b In cases, when the reaction mixture decomposed within 30 min of exposure to microwave irradiation, the yield was determined after 10 min.