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

Abstract

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.

Advances in the chemical and biological diversity of heterocyclic systems incorporating pyrimido[1,6-a]pyrimidine and pyrimido[1,6-c]pyrimidine scaffolds

“…An unpretentious method was conveyed for the synthesis of ethyl pyrano-pyrimido[6,1- b ]quinazoline-2-carboxylates (79) by Shi et al 69 through multi-step reactions. Consequently, condensation of aryl aldehydes 75 with malononitrile yielded the arylidene malononitriles 76 according to the procedure reported by Venkateswarlu et al 70 Arylidenes 76 were reacted with ethyl 3-oxobutanoate to afford the desired ethyl carboxylates 77.…”

“…The cyclization step followed an initial nucleophilic attack of the arylamino function of methyl 2-aminobenzoate at the ethoxymethylene carbon with the elimination of an ethanol molecule and subsequent intramolecular nucleophilic attack at the nitrile function to generate an imino group, which attacked the ester group to afford the target products 79 ( Scheme 19 ). 69 …”