Heterogeneous gold nanocatalyst applied in the synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones

Abstract

Gold nanocatalyst was efficiently applied in the synthesis of 2–aryl–2,3–dihydroquinazolin–4(1H)–ones using very small catalyst amount (0.6 gold mol%). These heterocyclic compounds, which can be synthesized by direct condensation of aromatic aldehydes with 2–aminobenzamide, have been recognized as core structure for medicinal drug development. The success of the nanocatalyst lies on its characteristics that allow the formation of small gold nanoparticles strongly adhered to the surface of SBA–15 material, in a highly dispersed way. For this, SBA–15 was modified with a thin coating of cationic silsesquioxane. This coating allows the immobilization of AuCl4− complex by ion-exchange. The offered gold amount was lower than the cationic coating capacity, thus ensuring that the gold amount added was totally anchored and converted into small nanoparticles during the reduction process. The presence of gold nanoparticles did not affect drastically the textural characteristics of the SBA–15, ensuring the diffusion of reactants and ensuing access to the reactive catalyst sites.