Abstract
A simple and efficient new synthetic method to obtain 3-substituted quinazolin-2,4-diones 9(-)16 by the reaction of 3-substituted 2-thioxo-quinazolin-4-ones 1(-)8 with sodamide under mild conditions was presented. The structure of the newly synthesized compounds was determined by infrared spectroscopy, UV-visible spectroscopy, nuclear magnetic resonance, and single-crystal X-ray crystallographic analysis. The crystal structure of 6-methyl-3-phenylquinazoline-2,4(1H,3H)-dione (11) [C15H12N2O2: MF = 252.27, triclinic, P-1, a = 7.8495 (13) angstrom, b = 12.456 (2) angstrom, c = 13.350 (2) angstrom, alpha = 103.322 (3)degrees, beta = 90.002 (3)degrees, gamma = 102.671 (4)degrees, V = 1237.5 (3) angstrom(3), Z = 4, R = 0.0592, wR = 0.1699, S = 1.039] was determined. In the crystal cell, two identical conformers of compound 11 were found connected by intramolecular hydrogen bonds, responsible for the favourable occurrence of these two independent molecules.