Sustainable catalytic process with a high Eco-Scale score for the synthesis of five-, six-, and Seven-Membered heterocyclic compounds using nanocrystalline zeolites

Abstract

Nanocrystalline ZSM-5 and Beta zeolites were evaluated as catalysts for the one-pot synthesis of a wide range of five-, six-, and seven-membered heterocyclic compounds. Seven-membered compounds were prepared by the reaction of o-phenylenediamine and ketones, whereas five-membered compounds were obtained when o-aminothiophenol was reacted with ketones under the same reaction condition. Several other seven-membered compounds were prepared by the reaction of (E)-chalcone with o-phenylenediamine/o-aminothiophenol, whereas the six-membered compounds described in this study were prepared by the reaction of o-phenylenediamine with 2-bromoacetophenone/2- hydroxy acetophenone. Two other five-membered compounds were prepared by the reaction of aniline with benzaldehyde and thioglycolic acid, and the reaction of glycerol with acetone. The mechanisms responsible for the formation of the different products were elucidated based on the results of time-dependent 1H NMR experiments. To the best of our knowledge, this work represents the first reported systematic assessment of the catalytic activity of nanocrystalline zeolites for the synthesis of heterocyclic compounds. Notably, the catalysts were readily recovered and reused without any considerable decrease in their catalytic activity. The high eco-scale score and low E-factor value of this process clearly demonstrate that it represents a green and sustainable synthetic route for the preparation of a wide range of heterocyclic compounds of significant industrial importance.