One-Pot-Condensation Reaction of Heterocyclic Amine, 1,3-Diketone and Aldehydes Using In Situ Generated Superoxide Ion: A Rapid Synthesis of Structurally Diverse Drug-Like Complex Heterocycles

Abstract

A novel, convenient one-pot multicomponent synthesis of tetraheterocy-clicbenzimidazolo/benzothiazolo quinazolin-1-one derivatives has been reported in the presence of tetraethylammonium superoxide under non-aqueous condition. The superoxide induced three-component reaction of various aromatic aldehydes, 2-aminobenzimadazole/2-aminobenzothiazole and dimedone/1,3- cyclohexane-dione produced tetraheterocyclicbenzimidazolo/benzothiazolo quinazolin-1-one derivatives at room temperature under the mild reaction conditions. The tetraethylammonium superoxide has been generated by phase transfer reaction of potassium superoxide and tetraethylammonium bromide in dry DMF at room temperature. The present study extended the applicability of tetraethylammonium bromide as a phase transfer catalyst for the efficient use of superoxide ion in multi-component synthesis of structurally diverse drug-like complex heterocycles (quinazolines). role of O 2 • − in living cells. Since the investigation has been performed at an ambient temperature in the presence of in situ generated O 2• − , the results may be easily correlated with those occurring at physiological temperatures in more complex biological counterparts. A novel synthetic route has been developed for the synthesis of tetraheterocyclic benzimidazolo/benzothiazolo quinazolin-1-one ring systems using tetraethylammonium superoxide under non aqueous condition at room temperature (mild reaction condition) within 6 h. The yield of the products was obtained up to 88% without using any tedious purification process. The applicability of tetraethylammonium bromide as an inexpensive alternative to 18-crown-6 for superoxide ion generation has been extended in present report.