An efficient metal-free synthesis of 2-amino-substituted-4(3 H )-quinazolinones

Aminonitrones as highly reactive bifunctional synthons. An expedient one-pot route to 5-amino-1,2,4-triazoles and 5-amino-1,2,4-oxadiazoles – potential antimicrobials targeting multi-drug resistant bacteria

A four-component one-pot reaction proceeds very rapidly under mild conditions and gives the heterocyclic systems in good yields.

Guanylation/cyclisation of amino acid esters using an imidazolin-2-iminato titanium initiator

Catalytic hydroamination of amino acid esters with carbodiimides and isocyanates to furnish corresponding quinazolinone and urea derivatives using two Ti^IV complexes under mild conditions is reported.

I2/TBHP-Mediated Oxidative Coupling of Amino-Based Bisnucleophiles and Isocyanides: Access to 2-Aminobenzoxazinones, 2-Aminobenzoxazines, and 2-Aminoquinazolines under Metal-Free Conditions

An I₂/ tert-butyl hydroperoxide (TBHP)-mediated oxidative coupling reaction of isocyanides with amino-based bisnucleophiles is described for the synthesis of 2-aminobenzoxazinones, 2-aminobenzoxazines, and 2-aminoquinozolines in moderate to excellent yields. Furthermore, this method provides a simple and practical method to construct potential functionalized biologically active molecules.

Facile selective synthesis of 2-methyl-5-amino-1,2,4-oxadiazolium bromides as further targets for nucleophilic additions

The reaction of aminonitrones with isocyanides and Br₂ gives 2-methyl-5-amino-1,2,4-oxadiazolium bromides, which are convenient precursors for other heterocycles and ureides.

Design, synthesis and antibacterial evaluation of 2-alkyl- and 2-aryl-3-(phenylamino)quinazolin-4(3H)-one derivatives

2-Alkyl and 2-aryl-3-(phenylamino)quinazolin-4(3H)-ones 4a–h were synthesized in a one-pot three-component condensation of an isatoic anhydride 1a–h, ethyl or methyl ortho ester and phenylhydrazine in the presence of KAl(SO4)2·12H2O (alum) as a nontoxic, reusable, inexpensive and easily available catalyst. The synthesis was conducted under microwave irradiation or classical heating. Products 4a and 4b show good antimicrobial activities.

Synthesis of Novel Ethyl 1-aryl-3-methyl-8-oxo-1,8-dihydropyrano[2′,3′:4,5] Pyrimido[6,1-b]Quinazoline-2-carboxylate Derivatives

In this paper, a new series of ethyl 1-aryl-3-methyl-8-oxo-1,8-dihydropyrano[2′,3′:4,5]pyrimido[6,1-b]quinazoline-2-carboxylate derivatives was synthesised by the cyclisation of methyl anthranilate with ethyl 5-cyano-6-[(ethoxymethylene)amino]-2-methyl-4-aryl-4H-pyran-3-carboxylate derivatives, which were obtained from reaction of triethyl orthoformate with 6-amino-5-cyano-2-methyl-4-aryl-4H- pyran-3-carboxylate derivatives. The title compounds possessed good fluorescence properties. In addition, ethyl 5-cyano-6-[(ethoxymethylene) amino]-2-methyl-4-(p-tolyl)-4H-pyran-3-carboxylate and ethyl 3-methyl-8-oxo-1-(p-tolyl)-1,8-dihydropyrano[2′,3′:4,5]pyrimido[6,1-b] quinazoline-2-carboxylate were further determined by single crystal X-ray diffraction analysis.