An eco-friendly and highly efficient approach for the synthesis of substituted imidazoles via nano zirconia catalyzed multicomponent reaction of isatin derivatives with ammonium acetate and aromatic aldehydes under solvent-free conditions has been developed. This approach can be mostly applied to medicinal chemistry due of the simple and readily available starting materials, effortless methodology, and biologically active nature of imidazoles. An additional gain of the suggested technique is the reusability of the nano ZrO2 catalyst.
Part of the book: Nanocatalysts
A novel, convenient one-pot multicomponent synthesis of tetraheterocyclicbenzimidazolo/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- cyclohexanedione 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).
Part of the book: Heterocycles