Synthesis of Bis-2,3-dihydroquinazolin-4(1H)-ones and 2,3-Dihydroquinazolin-4(1H)-ones Derivatives with the Aid of Silica-Supported Preyssler Nanoparticles

One-pot three-component condensation of isatoic anhydride with primary amines or ammonium carbonate and aromatic aldehydes in refluxing ethanol in the presence of catalytic amounts of silica-supported preyssler nanoparticles (SPNP) afforded the corresponding 2,3-dihydroquinazolin-4(1H)-ones in high yields, and bis-dihydroquinazolinones were synthesized for the first time by a novel pseudo-five-component condensation of isatoic anhydride, a primary amine, and a dialdehyde in water. The catalyst is reusable and can be applied several times without any decrease in product yield. 1. Introduction One-pot transformations, particularlymulticomponent reactions (MCRs), are of current interest by Salehi et al. [1]. Since the first MCR reported in 1850 by Strecker [2], this methodology has emerged as an especially attractive synthetic strategy for rapid and efficient library generation due to the fact that the products are formed in a single step and diversity can be achieved simply by varying the reaction components by Strecker [2]. MCRs leading to interesting heterocyclic scaffolds are particularly useful for the creation of diverse chemical libraries of drug-like molecules for biological screening by Domling [3]. 2,3-Dihydroquinazolinone derivatives are an important class of fused heterocycles that display a wide range of biological, pharmacological, and medicinal properties involving antitumor, antibiotic, antipyretic, analgesic, antihypertonic, diuretic, antihistamine, antidepressant, and vasodilating activities by Sadanandam et al. [4]. In addition, 2,3-dihydroquinazolinones have been shown to act as potent tubulin inhibitors with impressive antiproliferative activity against several human cancer cell lines by Chinigo et al. [5]. Furthermore, these compounds can act analogously to the antimitotic agent colchicine [6]. Additionally, these compounds can easily be oxidized to their quinazolin-4(3H)-one analogues by Baker et al. [7], which are themselves important biologically active heterocyclic compounds, Moore et al. [8]. The usual procedure for the preparation of 2,3-dihydroquinazolin-4(1H)-ones involves condensation of the appropriate derivatives of anthranilamide with an aldehyde or ketone using p-toluenesulfonic acid as a catalyst under vigorous conditions, by Ozaki et al. [9]. Similar reactions have been reported to proceed under basic conditions, by Kornet [10]. This procedure affords dihydroquinazolinones in good yields but requires long reaction times. The three-step synthesis starting from isatoic anhydride or an anthranilic acid has been reported by