Synthesis of some new heterocycles containing quinazoline moiety

Abstract

The presented herein synthesis of new quinazolines and quinazolino[3,4-a]quinazolines started from 2-amino-N-alkylbenzamides. Reaction of 2-amino-N-alkylbenzamides with 2-nitrobenzaldehyde followed by reduction using Zn afforded the corresponding 3-alkyl-2-(2-aminophenyl)-2,3-dihydroquinazolin-4(1H)-ones. Cyclization of the later compounds with carbon disulfide followed by methyl iodide, triethyl orthoformate or dimethyl acetylenedicarboxylate (DMAD) gave new quinazolino[3,4-a]quinazoline derivatives that were characterized on the basis of FT-IR, ¹H, and ¹³C NMR spectra, and microanalytical data. In the case of reaction with DMAD, 2D nuclear Overhauser effect (2D-NOESY) spectrum together with comparison of the experimental and calculated chemical shifts at the B3LYP/6-311+G(d,p) level of theory were also used to identify the correct stereoisomer.